0.159     2015-05-11  Ricardo Signes    <rjbs@cpan.org>

        - deal with >4b APP0 (thanks, isync!)
        - add metadata to distribution
        - clean up pod abstracts

2014-05-12  Ricardo Signes    <rjbs@cpan.org>

  * avoid useless use of ? modifier on fixed-length {n} repetition
    in regex; avoids a warning in 5.20.0

2014-02-04  Ricardo Signes    <rjbs@cpan.org>

  * avoid having output corrupted by assignment to $,

2014-02-02  Ricardo Signes    <rjbs@cpan.org>

  * only run Pod::Checker tests when releasing
  * encode all source at UTF-8, including comments
  * add =encoding directives to Pod where needed

2009-06-18  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm: setting $VERSION to 0.153, and
	posting to CPAN (this is mainly a bugfix version, being up-
        loaded after three years due to lack of interest from users).
        Most relevant changes from version 0.15 to 0.152:
	(see the documentation in the .pod files for more details)
        * eliminated all annoying errors in the test suite. 
	* added t/test_setup.pl to the MANIFEST (sorry version 0.151)
	* updated Test::More related code (sorry version 0.152)
	* fixed bug #17835 (see rt.cpan.org)
	* new documentation: 'Structure of an XMP APP1 segment'
	* new documentation: 'XMP data ("APP1" segments)'
	* new (very preliminary) subsystem for parsing XML data
        * new possibilities for the APP13 signature ('8BPS', 'PHUT').
          Parser, dumper, tables and documentation changed accordingly.
	* general reorganisation of files in the project.

2009-06-16  Stefano Bettelli  <bettelli@cpan.org>

        * t/*.t: these tests were all failing due to some change
        (that happened approximately two years ago) in the way
        module symbols are imported by Test::More::use_ok. 
        I have moved some input code into a common file named

2006-05-14  Stefano Bettelli  <bettelli@cpan.org>

	* saved as version 0.15a and sent to Martin for comments.

	* t/JPEG_4_app13.t: changed $APP13_PHOTOSHOP_DIRNAME into

	* lib/Image/MetaData/JPEG/access/app13.pl (sanitise_what): updated
	list of allowed values for $what: 'IPTC', 'IPTC_2', 'IPTC_1',
	(subdir_name): updated to return the new $what --> subdir corresp.:
	'IPTC'      => $APP13_IPTC_DIRNAME . '_2'         # synonym
	'IPTC_1'    => $APP13_IPTC_DIRNAME . '_1'	  
	'IPTC_2'    => $APP13_IPTC_DIRNAME . '_2'	  
	(get_app13_data): updated, so that, if $what is "non-IPTC", the
	"extra" values for each record are appended, according to the tag.
	I.e., use "if ($what!~/IPTC/)" instead of "if ($what eq 'PHOTOSHOP')".
	(set_app13_data): same thing, when testing for "non-IPTC"-ness.
	(insert_accepted): same thing, when testing for "non-IPTC"-ness.
	(value_is_OK): same thing, when testing for "non-IPTC"-ness.

	* lib/Image/MetaData/JPEG.pod: section "Photoshop and IPTC data
	- ("APP13" segments)" modified to introduce new $what values:
	Recent versions of Photoshop (>= 4.0) use a resource data block
	type equal to '8BIM', and this is the default in this module (so,
	'PHOTOSHOP' and 'PS_8BIM' are synonyms). However, some other older
	or undocumented resource data block types are also allowed. Currently
	allowed valuse are: 'PS_8BIM'='PHOTOSHOP', 'PS_8BPS' and 'PS_PHUT'.
	See also allowed $what values in section "How to inspect and modify
	your Photoshop data".

	* lib/Image/MetaData/JPEG/dumpers/app13.pl (dump_app13): update to
	cope with the new structure of APP13 for non-IPTC (Photoshop) data.
	Now, all non-IPTC subdirs, named "${APP13_PHOTOSHOP_DIRNAME}_${type}"
	for $type in @$APP13_PHOTOSHOP_TYPE, are searched in sequence and
	dumped via $this->dump_resource_data_block ($type is a new argument).
	The dump sequence for IPTC data was also simplified a bit.
	(dump_resource_data_block): the Photoshop resource data block
	type (sometimes named OS_type) is no more fixed to '8BIM', but
	is passed in the second argument. If it is missing, it defaults
	to $$APP13_PHOTOSHOP_TYPE[0], that is '8BIM', as before.

	* lib/Image/MetaData/JPEG/parsers/app1_xmp.pl (parse_rdf_description): 
	some top-level rdf:Description's are there as placeholders (there
	is only an empty CONTENT before the closing tag). In this case, 
	the property-extraction stage must be skipped. The consequence is
	that we will have a namespace entry under 'SCHEMAS' but no property
	with that prefix under 'PROPERTIES'.

2006-05-11  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/data/Tables.pm : updated to take into
	account the new location of non-IPTC tags in an APP13 segment:
        my $JPEG_RECORD_NAME =
        {APP1  => {%$HASH_APP1_ROOT, .....
	           $APP13_IPTC_DIRNAME.'_1'         => $HASH_IPTC_TAGS_1,
	           $APP13_IPTC_DIRNAME.'_2'         => $HASH_IPTC_TAGS_2,},};
	* lib/Image/MetaData/JPEG/data/Tables.pm : the $APP13_PHOTOSHOP_TYPE
	constant is now a reference to an array containing accepted strings
	for a resource data block type. Currently, its value is the following:

	* lb/Image/MetaData/JPEG/parsers/app13.pl (parse_resource_data_block): 
        The content of each Photoshop non-IPTC data block is transformed
	into a record and stored in a first-level subdirectory, depending
	on its type. The block type is, in fact, no more supposed to be
	'8BIM'; however, only some known values are accepted. See the
	variable $APP13_PHOTOSHOP_TYPE in Tables.pm
	* lib/Image/MetaData/JPEG/Structures.pod: new note on resource
	data block types in APP13, claryfing that 8BIM is only the default:
	"The signature (type) is usually '8BIM', but Photoshop used '8BPS'
	up to version 3.0, and some rogue program (Adobe PhotoDeluxe?) is
	using 'PHUT' for path information (ID=7d0-bb7)."

2006-04-29  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/dumpers/dumpers.pl: the content of this
	file is now broken down into separate pieces, which are 'require'd
	here (that is, included): app1.pl, app1_exif.pl, app13.pl.

	* lib/Image/MetaData/JPEG/parsers/parsers.pl: the content of this
	file is now broken down into separate pieces, which are 'require'd
	here (that is, included): image.pl, app0.pl, app1.pl, app1_exif.pl, 
	app1_exif_xmp.pl, app2.pl, app3.pl, app12.pl, app13.pl, app14.pl.

	* lib/Image/MetaData/JPEG.pm: general reorganisation of files in
	the project. New subdirs 'data', 'parsers', 'dumpers' and 'access'
	created under 'JPEG'. The following use statements updated all 
	over the project (prefix is always Image::MetaData::JPEG::) :
	Tables               --> data::Tables
        Tables_makernotes.pl --> data/Makernotes.pl
        Segment_parsers.pl   --> parsers/parsers.pl
        Segment_dumpers.pl   --> dumpers/dumpers.pl
	JPEG_various.pl      --> access/various.pl
        JPEG_comments.pl     --> access/comments.pl
	JPEG_app1_exif.pl    --> access/app1_exif.pl
	JPEG_app13.pl        --> access/app13.pl

2006-04-09  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm: new constants:
	$APP1_XMP_XPACKET_ID = 'W5M0MpCehiHzreSzNTczkc9d'
	$APP1_XMP_META_NS = 'adobe:ns:meta/'
	$APP1_XMP_OUTER_RDF_NS = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'
	TagsAPP1 was broken into TagsAPP1_Exif and TagsAPP1_XMP. 
	Relevant changes applied to JPEG_app1_exif.pl,
	Segment_dumpers.pl and Segment_parsers.pl.
2006-04-08  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Structures.pod: completed syntax
	description for the structure of an APP1 XMP segment.

2006-04-01  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Structures.pod: added a new section
	with title 'Structure of an XMP APP1 segment'.

	* lib/Image/MetaData/JPEG.pod: started a new section with title:
	'XMP data ("APP1" segments)', containing a very short description
	of what is XMP and how it is used in JPEG files.

	* t/JPEG_2_JPEG_class.t: explicit initialisation to "" of scalars 
	whose reference is passed to JPEG::save (see bug #17835). Same 
	change for t/JPEG_5_exif_Thumbnail.t, t/JPEG_5_exif_SubIFD.t,
	t/JPEG_5_exif_GPS.t, t/JPEG_5_exif_IFD.t, t/JPEG_5_exif_IMAGE.t,
	t/JPEG_5_exif_Interop.t, t/JPEG_4_app13_set.t, t/JPEG_3_comments.t
2006-03-27  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app1_xmp): new
	routine for parsing XML data. This is more clean and logical, I 
	hope. It uses parse_xml_string() internally. Comments to be added.

2006-02-28  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_thumbnail): 
	explicitely initialise $r to an empty string. See bug #17835 on
	rt.cpan.org concerning Image::MetaData::JPEG. Thanks to Brian Carp
	for the related discussion. Other changes still to implement.
2006-01-06  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm: setting $VERSION to 0.15, and
	posting to CPAN (as soon as my network connection is working).
        Most relevant changes from version 0.141 to 0.15:
	(see the documentation in the .pod files for more details)
	* IPTC data treatment in APP13 segments extended to deal with more
	  exotic IPTC record numbers (i.e., other than 2). IPTC setters and
	  getters (set/get_app13_data) updated to allow for the insertion of
	  datasets with record number = 1; this provides low level support
	  for coded character sets (e.g., Unicode strings in IPTC).
	* Thumbnail replacement via set_Exif_data() made easier; a JPEG
	  object reference is now accepted as an alternative to a scalar
	  reference to a (valid) JPEG stream.
	* Check on the segment length being valid moved to update(). This
	  anticipates the error condition at the time data is set, not at
	  the time data are written on disk.
	* Revised rules for accepted and rejected dates (years). 'DateTime',
	  'DateTimeOriginal', 'DateTimeDigitized', 'GPSDateStamp', as well
	  as 'DigitalCreationDate', 'ReleaseDate' and 'ExpirationDate' 
	  can be set to a date >= 1800AD. The IPTC 'DateCreated' dataset 
          accepts the full ISO-8601 YYYY-MM-DD format (from 0AD on).
	* update() is called only once with 'IMAGE_DATA' in set_Exif_data.
	* Bugfix: the standard value for 'XResolution' and 'YResolution'
	  is [72, 1], not [1, 72] as before.
	* Documentation updates: more documentation on canonical IFD0 and
	  IFD1 tags, on DX3900 Makernotes, on Image::ExifTool capabilities,
	  more documentation and tests on IPTC and APP13, more examples in
	  the main .pod file.
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): new,
	strictly private, argument (4th). If set, the update() routine is
	not called. It is used by set_Exif_data() itself when called with
	$action eq 'IMAGE_DATA', so that update() can be called only once.
	* t/JPEG_5_exif_IMAGE.t: added a new test to check that update()
	is really called only once when $action is 'IMAGE_DATA'.

2006-01-05  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/TagLists.pod: notes added to the "Canonical
	Exif 2.2 and TIFF 6.0 tags for IFD0 and IFD1" section. Clarifications
	for 'DateTime', 'DateTimeOriginal', and 'DateTimeDigitized' added.

        * copyright extended to 2006 in all relevant files.
        * moved to Vienna.
2005-12-18  Stefano Bettelli  <bettelli@cpan.org>

        * saved as version 0.141c and sent to D.Manpearl for comments.
	* lib/Image/MetaData/JPEG.pod: new example on how to display all
	items from a repeatable IPTC record (under get_app13_data).

	* lib/Image/MetaData/JPEG.pod: the documentation of set_Exif_data
	now explains the new way to deal with thumbnails. There is also an
	example of how to set and delete a thumbnail.

	* t/JPEG_5_exif_Thumbnail.t: two set_Exif_data calls changed: the
	argument is now a reference to a JPEG object. This tests the 
	previous modification for set_Exif_thumbnail.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_thumbnail): 
	the argument can now be a reference to an Image::MetaData::JPEG
	object. In this way, if you want to set a thumbnail from an already
	existing object you don't need to extract the stream yourself.
	Thanks to David Manpearl for suggestions on this interface.
2005-10-26  Stefano Bettelli  <bettelli@cpan.org>

	* saved as version 0.141b and sent to Martin for comments.

	* lib/Image/MetaData/JPEG.pod: section on update() updated.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl: trivial modifications
	in some routines. Specialised dumpers now return 'undef' when there
	are no problems and a message when there is a problem.

	* lib/Image/MetaData/JPEG/Segment.pm (update): this method now
	saves a reference to the old segment data area and restores it if
	the specialised update routine fails. This only generate a warning!
	Are there cleverer ways to handle this case? It is however better
	to have a corrupt object in memory, than a corrupt object written
	over the original. Currently, this is restricted to the possibility
	that an updated segment becomes too large, but all specialised
	routines must nevertheless return 'undef' meaning there was no error.

	* lib/Image/MetaData/JPEG/Segment.pm (set_data): the 'OVERWRITE'
	option and the second argument are gone. This method can now be
	used only to append new data to the segment data area. Blanking
	the area must be a task for the general update() routine.
	Appropriate changes to Segment_sumpers.pl applied.

	* lib/Image/MetaData/JPEG/Tables.pm: new module variable for the
	maximum length of the data area of a standard JPEG segment (this
	does not apply to entropy-coded data and past-the-end "segments").
	$JPEG_SEG_MAX_LEN = 2**16 - 3; exported via the JPEGgrammar tag.

2005-10-26  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_app13_data): testing
	explicitely for a dataset not being 'IPTC/NAA' is no more necessary.
	Insertion of mandatory datasets much simplified and more robust.
	(insert_accepted, screen_data): these new routines or methods
	contain now some of the code previously belonging to set_app13_data,
	which was really getting too big.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (value_is_OK): don't test
	whether $what is /^IPTC/ or not, just look for a syntax definition
	for the tag. This makes the routine more robust. Skipping the test
	on the second value for $what='PHOTOSHOP' is a bit hackish though.

	* lib/Image/MetaData/JPEG/Tables.pm: syntax specifications added to
	%$HASH_PHOTOSHOP_GENERAL. They are currently just placeholder, but
	this could change in future. The only effect is to inhibit a direct
	assignement of the 'IPTC/NAA' dataset, which must be modified with
	specialised routines.
2005-10-25  Stefano Bettelli  <bettelli@cpan.org>

	* saved as version 0.141a

	* lib/Image/MetaData/JPEG.pod: prepared a clearer (?) and more
	consistent SYNOPSIS (thanks to Julio Otuyama for this remark).

	* lib/Image/MetaData/JPEG/TagLists.pod: trivial changes to
	be consistent with the new rules on dates and centuries.

	* t/JPEG_4_app13_IPTC.t: more tests on 'DigitalCreationDate',
	'ReleaseDate', 'ExpirationDate', and expecially 'DateCreated'.
	* t/JPEG_5_exif_GPS.t: more tests on 'GPSDateStamp'.
	* t/JPEG_5_exif_IFD.t: more tests on 'DateTime'.
	* t/JPEG_5_exif_SubIFD.t: more tests on 'DateTimeOriginal/Digitized'.

	* lib/Image/MetaData/JPEG.pod: NOTES section added, with a 
	discussion on date setting and the notes on MakerNote corruption
	which were previously written in MakerNotes.pod.

	* lib/Image/MetaData/JPEG/Tables.pm: reorganisation of regular
	expressions for date fields. The $re_year regular expression was
	renamed to $re_yr18 and changed to '(18|19|20)\d\d'; this allows
	'DateTime', 'DateTimeOriginal', 'DateTimeDigitized',
	'GPSDateStamp', 'DigitalCreationDate', 'ReleaseDate' and
	'ExpirationDate' to be set to a date from 1800AD on, and not from
	1900AD as before. The IPTC 'DateCreated' dataset uses now a
	different regular expression ($re_year = '\d{4}') which allows a
	date in the full ISO-8601 YYYY-MM-DD format (from 0AD on). Have a
	look at the note in the main pod document for further details.
	Special thanks to Ian Cameron Smith for a long discussion on this
	subject; however, I am still open to suggestions and

	* lib/Image/MetaData/JPEG.pod: changed the description of
	Image::ExifTool, which has write capabilities since early 2005.

	* t/JPEG_4_app13_IPTC.t: some new tests for IPTC_1/IPTC_2 (800+!)

	* t/JPEG_4_app13.t: some new tests for IPTC_1/IPTC_2

	* lib/Image/MetaData/JPEG/Structures.pod: (very small) update

	* lib/Image/MetaData/JPEG.pod: documentation updated for IPTC.

2005-10-24  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (shift_non_repeatables): 
	new second argument $what, needed for retrieving syntax tables.
	(value_is_OK): minimal changes to retrieve the correct syntax tables.
	(set_app13_data): minimale changes to be ready for multiple IPTC
	subdirectories; more systematic treatment of mandatory datasets.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (provide_app13_subdir): 
        the initialisation of a subdirectory can include mandatory records,
	which are now read from Tables.pm and not hardcoded here as it used
	to be. The actual insertion is done via set_app13_data.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (sanitise_what): $what can
	be 'IPTC_2' (or 'IPTC' for back. compat.), 'IPTC_1' or 'PHOTOSHOP'. 
	(subdir_name): the correct subdirectory is returned for both
	'IPTC_1' and 'IPTC_2' ('IPTC'): $APP13_IPTC_DIRNAME.'_1' or .'_2'

	* lib/Image/MetaData/JPEG/Tables.pm: syntax tables and mandatory
	records tables for IPTC data are now hidden in the corresponding
	tag hashes, that is (for instance, for IPTC_1):
	$$HASH_IPTC_TAGS_1{__syntax}    = $HASH_IPTC_GENERAL_1;
	$$HASH_IPTC_TAGS_1{__mandatory} = $HASH_IPTC_MANDATORY_1;  

	* lib/Image/MetaData/JPEG/Tables.pm (str2hex): "mandatory" datasets
	my $HASH_IPTC_MANDATORY_1 = {'ModelVersion'  => "\000\004" };
	my $HASH_IPTC_MANDATORY_2 = {'RecordVersion' => "\000\002" };
	I don't know why the standard says 4 for 'RecordVersion'; 
	it turns out that you always find 2 in JPEG files.

2005-10-23  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_IPTC_datasets): 
	modified to deal with IPTC record numbers other than 2. The record
	number is now passed as first argument. 

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app13): modified
	to cope with multiple IPTC records (in increasing numerical order).

	* lib/Image/MetaData/JPEG/TagLists.pod: tag descriptions and notes
	added for datasets in IPTC envelop records; the most important item
	is the coded character set dataset, selecting the "alphabet".

	* lib/Image/MetaData/JPEG/Tables.pm: changed HASH_IPTC_TAGS and 
	HASH_IPTC_GENERAL to take into account other IPTC records. This
	is needed for supporting IPTC records different from two. Dataset
	curriculum for record = 1 introduced in $HASH_IPTC_GENERAL_1.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_IPTC_dataset): 
	this routine now takes one argument ($offset). $dirref is calculated.
	Each dataset is saved in the corresponding record subdirectory.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_IPTC_dataset): 
	new format for storing IPTC data. Given that I have found pictures
	with records != 2, data-sets are now not all stored directly in the
	$APP13_IPTC_DIRNAME = "IPTC_RECORD" directory, but in an appropriate
	"${APP13_IPTC_DIRNAME}_${rnumber}", where $rnumber is the record
	number (currently, only records 1 and 2 have been observed). Of
	course, for most pictures only the IPTC_RECORD_2 subdirectory will
	be populated. Obviously, the "IPTC record != 2 ..." error is now gone.
	This implies a number of changes in other routines too ...

2005-08-16  Stefano Bettelli  <bettelli@cpan.org>

	* t/test_photo.desc: changed the 'PanoramaMode' and 'Sharpness'
	lines to SSHORT, to reflect the changes in Tables_makernotes.pl. I
	guess I should run tests a bit more often ...

	* lib/Image/MetaData/JPEG/Tables.pm: changed the 'XResolution' and
	'YResolution' default values in $HASH_APP1_IFD01_MANDATORY to [72,
	1]; tests updated (they were [1, 72], thanks to Ian Cameron Smith
	for finding this error).
2005-04-09  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/MakerNotes.pod: new section on the 
	meaning of tag values for the DX3900 Kodak camera.

	* lib/Image/MetaData/JPEG/Tables_makernotes.pl: 'PanoramaMode' for
	Kodak cameras is now $SSHORT in '(0|-1)'; 'Sharpness' for Kodak
	cameras is now $SBYTE in '(-1|0|1)'. Arbitrary but simpler ...

2005-03-21  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm: setting $VERSION to 0.141,
	and posting to CPAN. This is only a minor bugfix release.
        Most relevant changes from version 0.14 to 0.141:
        * rt.cpan.org bug #11950 fixed
        * Descriptions in documentation annexes fixed.
	* lib/Image/MetaData/JPEG/Structures.pod: modify the description,
	so that the first line contains the real description for this 
	document and not the note about it being an appendix. Same change
	in TagLists.pod and MakeNotes.pod.

	* t/JPEG_5_exif_GPS.t: a few tests added for correct limits on
	longitudes and latitudes after closing the bug.

	* lib/Image/MetaData/JPEG/Tables.pm: closing rt.cpan.org bug #11950,
	"GPSLongitude field being dropped" (thanks to John Harvey). The
	special rule for longitudes is not the same as that for latitudes,
	because the limit is 180deg and not 90deg. Replaced $SSR_latlong
	with $SSR_latitude (for 'GPSLatitude' and 'GPSDestLatitude') and
	$SSR_longitude (for 'GPSLongitude' and 'GPSDestLongitude').

	* lib/Image/MetaData/JPEG/TagLists.pod (GPS tags): Latitudes are
	limited to the interval [0,90], while longitudes to [0,180].

2005-03-16  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm: setting $VERSION to 0.14, and posting
	to CPAN. This should be in sync with next version of MaPiVi now.
        Most relevant changes from version 0.13 to 0.14:
	* New naming of top level keys in get_Exif_data when $what eq
	  'ALL' in get_Exif_data: the returned keys are now equal to $what.
	* Implementation of MakerNote parsing; possibility to retrieve
	  MakerNote information via get_Exif_data (by setting $what eq
	  'MAKERNOTE_DATA'). However, the content is not currently modifiable.
	* Prediction mechanism for semi-corrupted MakerNotes.
	* New and more sensible algorithm for find_new_app_segment_position
	* Better warning and error messages; ability to exclude warning
	  generation by setting $JPEG::show_warnings to undef.
	* Older PhotoShop identifier accepted when parsing an APP13
	  segment (used by Photoshop version 2.5).
	* Algorithm for skipping a few bogus bytes before a segment
	  marker (this bug is sometimes found after comment segments).
	* Warning instead of error for prematurely terminating
	  JPEG streams (e.g. truncated files)
	* New argument order for search_record/search_record_value:
	  the optional directory reference is now the last argument.
	* Correction of a bug in Record::get_description corrected
	  (reference values were not printed correctly).
	* New documentation section on the history of JPEG image file formats
	* Script 'read_JPEG_metadata' added to distribution

2005-03-07  Stefano Bettelli  <bettelli@cpan.org>

	* saved as version 0.13e (unless Martin finds bugs or asks for
	changes, this will be next release, i.e. version 0.14).

	* lib/Image/MetaData/JPEG.pod: ispell-ed
	* lib/Image/MetaData/JPEG/MakerNotes.pod: ispell-ed

	* lib/Image/MetaData/JPEG/Structures.pod: added a section on the
	history of JPEG image file format standards + ispell-ed

	* lib/Image/MetaData/JPEG.pm (parse_ecs): if the end of the
	compressed stream is not found, complain but do not fail (similarly
	to the 'xv' program); the file is however corrupt and unusable.
	* lib/Image/MetaData/JPEG/Segment.pm (new): pay attention! the
	first argument in the constructor (the old parental link) is now
	gone. All relevant tests were updated: t/JPEG_1_segments.t,
	t/JPEG_2_JPEG_class.t, t/JPEG_5_exif_IFD.t, t/JPEG_5_exif_IMAGE.t,
	t/JPEG_5_exif_Interop.t, t/JPEG_5_exif_SubIFD.t,t/JPEG_2_rare.t;
	new test count is 780.
	* lib/Image/MetaData/JPEG/TagLists.pod: new note about SubIFD's
	Pixel[XY]Dimension: this is the valid width or height of the
	meaningful image (horizontal dimension does not include data
	padding). Overall image dimensions can be read in the SOF
	segment (this includes padding however).
	* lib/Image/MetaData/JPEG.pod: removed paragraph on Segment's parent.
	Modified SUBIFD_DATA's notes on 'PixelXDimension'/'PixelYDimension'
	which now state: "Image dimensions can be retrieved from the SOF
	  segment with the JPEG structure object's method get_dimensions()
	  and set explicitely by the user (this cannot be done from within
	  the APP1 segment, because it does not link back to its parent);
	  however, the horizontal field in the SubIFD should not include data
	  padding, while that in the SOF segment does, so the meaning is a
	  bit different and these fields cannot be automatically calculated."
	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP1_SUBIFD_MANDATORY): 
	the default value of 'PixelXDimension' and 'PixelYDimension' is 
	now set to zero (this is a piece of information which only the
	whole JPEG object can find, not a single segment; it must be set
	by the user or by a JPEG object level method).

	* lib/Image/MetaData/JPEG.pm: removed any trace of the "parental"
	link in the Segment constructor. This avoids the problem of circular
	references versus garbage collection and a lot of user level pain
	just to set the image dimensions in a SubIFD starting from a segment.
	Indeed, it seems it is the whole idea of having segments pointing
	back to JPEG objects which is rotten: if a transformation requires
	global knowledge, it is to be applied on a JPEG object. Same in:
	   lib/Image/MetaData/JPEG/JPEG_app13.pl (provide_app13_segment)
	   lib/Image/MetaData/JPEG/JPEG_comments.pl (add_comment)
	   lib/Image/MetaData/JPEG/JPEG_comments.pl (set_comment)
	   lib/Image/MetaData/JPEG/Segment.pm (info)
	   lib/Image/MetaData/JPEG/Segment.pm (new)

2005-02-28  Stefano Bettelli  <bettelli@cpan.org>

	* saved as version 0.13d (sent to dalibor.cz, this is a condition
	for being allowed to use Minolta MakerNote information).

	* lib/Image/MetaData/JPEG/MakerNotes.pod: reformatted + some info
	moved here from Tables_makernote.pl. Not yet the definitive MakerNote
	resource in the world, but better than nothing ...

2005-02-16  Stefano Bettelli  <bettelli@cpan.org>

        * saved as version 0.13c (release candidate 1 for 0.14); sent to
	Martin for pre-release comments. MakerNotes.pod still to write ...
	* t/JPEG_5_exif_Makernote.t: basic test file (44 tests) for
	MakerNotes; this should be enough for this release. These tests
	need a few supporting .jpg files (only the APP1 IFD0 is saved).
	Their "weight" is only 9599 bytes.

2005-02-15  Stefano Bettelli  <bettelli@cpan.org>

	* t/JPEG_2_JPEG_class.t: one more test on the correct behaviour
	of find_new_app_segment_position in provide_app1_Exif_segment.

	* t/JPEG_2_rare.t: added an APP13 with the old style identifier
	'Adobe_Photoshop2.5:' into t/test_frankenstein.jpg, and a test
	in JPEG_2_rare.t to be sure that it is read without errors.

	* t/JPEG_2_rare.t: 10 new tests on JPEG::get_next_marker (skipping
	a small amount of garbage, exiting on a large amount and no next
	marker), on JPEG::parse_segments not trying to read past the end
	of the file, and on the two new code snippets (unlink_segment and
	link_segment) in JPEG.pod.

	* lib/Image/MetaData/JPEG.pm (parse_segments): explicitely test that
	there is enough data before reading the segment size and data.

	* t/JPEG_1_segments.t: 5 new tests on the correct behaviour of
	provide_subdirectory and search_record_value with respect to the
	new approach of process_search_arguments.

	* t/JPEG_0_records.t: 14 new tests on error generation in Record.pm.

	* lib/Image/MetaData/JPEG/Record.pm (new): if the relevant argument is
	not a reference, an error is generated (instead of returning silently).

	* lib/Image/MetaData/JPEG/Record.pm (encode_integers): bug correction:
	the condition of wrong endianness was not trapped correctly!

2005-02-14  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/MakerNotes.pod: this documentation file
	is still to be reworked. It should contain (and expand) the comments
	which are now disorderly written in JPEG/Tables_makernotes.pl.

	* lib/Image/MetaData/JPEG.pod: documentation sync 0.13 --> 0.13b.
	* lib/Image/MetaData/JPEG/Backtrace.pm ($show_warnings): assigned
	$show_warnings to the JPEG package (although it is still physically
	declared in the Backtrace package source file) so that it is more
	easily addressed; modifications to: JPEG.pm, Segment.pm, Record.pm.
	All relevant tests updated (they must refer to the new variable).
2005-02-13  Stefano Bettelli  <bettelli@cpan.org>

        * saved as version 0.13b; documentation and tests still missing.
	* lib/Image/MetaData/JPEG.pm (get_next_marker): modified to
	be sure not to try to read past the end of the file.

	* lib/Image/MetaData/JPEG/Tables.pm (JPEG_lookup): do not delete
	the last element of the search path, even if it is false (some
	tags can be zero).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app13): when
	reading the identifier, don't try to read more bytes than available.

	* t/JPEG_1_segments.t : tuned all existing tests (even in all
	other .t files) to accept the previous changes. Most changes
	consisted simply in regenerating t/test_photo.desc.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): simmetrically,
	the meaning of the last argument, which specifies how the next_link
	pointer is to be treated, was changed ['0' --> the pointer is dumped
	with a non zero value; '1' --> the pointer is dumped with value set
	to zero; '2' -->: the pointer is ignored].

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd_children): 
	transform the warning about 'Jumping back' into a real error.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_interop): if
	there is a remote data area, and the prediction mechanism is enabled,
	use the prediction structure to set the value of $doffset; if the
	mechanism is disabled, die if $doffset points before the first
	prediction (this is very likely an address corruption).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): the two
	optional arguments are now to be interpreted in the following way:
	the first one specifies how the next_link pointer is to be treated
	['0': the pointer is read; '1': the pointer is read and a warning
	is issued if it is non-zero; '2': the pointer is not even read];
	{parse_makernote() was changed accordingly}
	the second one specifies whether the prediction mechanism for
	interoperability offsets should be used or not. However, a three
	element array is now always passed to parse_interop() for prediction,
	with the following meaning: [0] = if set, use predictions to rewrite
	addresses; [1] = value for next address prediction; [2] = old
	interoperability array address.
	{parse_interop() was changed accordingly}

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): take
	no_next into account when calculating the first prediction: if
	there is no next link, you must not add the last four bytes!

2005-02-12  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): new argument
	named next_link: 1 --> setup "next link" for another IFD, 0 --> setup
	"next link" to zero, -1 --> do not even write the four "next link"
	bytes (necessary for MakerNotes); dump_makernotes changed accordingly.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (provide_app1_Exif_segment)
	this function did not use the standard routine in JPEG.pm (i.e.,
	find_new_app_segment_position) for choosing a position for a new
	APP1 segment; its behaviour can now be standardised, given the
	improved behaviour of JPEG::find_new_app_segment_position().

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): bug found
	and corrected: when looking for thumbnail tags (location and length),
	one must explicitely check that the IFD name is 'IFD1', since records
	with the same tag (and different meaning) can be present in other
	IFD's, for instance in the MakerNote.
	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app1_exif):
	the identifier is now dumped directly by this routine, not by
	dump_TIFF_header(), since it was decided that the identifier
	is NOT part of the TIFF header.

	* lib/Image/MetaData/JPEG/Record.pm (get_size): added a trap for
	undefined types (this is only for debugging, obviously ...)

2005-02-11  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_makernote) this
	new routine is called by dump_ifd and is able to dump all kinds of
	makernotes that parse_makernote was able to parse. If the MakerNote
	scheme was unknown or there was an error at parse time, the MakerNote
	is copied as-is (this implies no recalculation of offsets ...).
	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): when
	REFERENCE records are transformed back to offsets, only those records
	with a non-undef extra field are to be considered (for MakerNotes).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_makernote):
	I changed my mind again: special MakerNote records are stored
	in a subdir of the MakerNote directory, named like

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_TIFF_header):
	relevant records are now searched for in the directory specified
	by the second argument (extension for MakerNotes).

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): modified
	to detect the presence of a MakerNote subdirectory and to delegate
	its dump to a more specific routine (dump_makernote).

2005-02-10  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm (JPEG_lookup): generalised as
	process_search_args: all undefined arguments are eliminated before
	joining, and all empty elements are eliminated after splitting.
	This makes the function much more robust (documentation?)

	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP1_SUBIFD_GENERAL):
	editing of 'MakerNote' currently disabled (pseudo-regex set to
	'invalid'); it will be probably re-enabled with a special $what,

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): if the
	current path is found to be invalid, it is given a second try assuming
	the last part is just the beginning of a tag (this is needed for
	MakerNote). One can now extract MakerNote information with $what set
	to 'MAKERNOTE_DATA' (get_Exif_data automatically understands if the
	correct subdir is MakerNoteData_Canon or MakerNoteData_Kodak or ...
	Also: the numeric-to-textual translation is performed only for those
	tags which are numeric (i.e., =~ /^\d+$/); because now we have text-
	only tags outside the root subdir.

2005-02-09  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment.pm (search_record): the returned
	$record is initialised with a fake $REFERENCE record A pointing
	to $this->{records}; so $this->search_record() returns A, and
	$this->search_record_value() returns $this->{records}. This
	should be added to the documentation!
	* lib/Image/MetaData/JPEG/Segment.pm (process_search_args): no
	arguments is now equivalent to (undef) instead of generating an
	error; all undef or "false" arguments are simply discarded. So,
	$this->provide_subdirectory() returns $this->{records}.

	* lib/Image/MetaData/JPEG/Tables.pm (%IFD_SUBDIRS): changed my mind
	again, the subdirectory corresponding to 'MakerNote' will be 
	'MakerNoteData', and will be specialised in 'MakerNoteData_format'.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): the
	first level keys in the hash returned by get_Exif_data when $what
	is set to 'ALL' are now coincident with the sub-$what's, that is
	'ROOT_DATA', 'IFD0_DATA', 'SUBIFD_DATA', ... instead of 'APP1',
	'APP1@IFD0', 'APP1@IFD0@SubIFD', ... Documentation (both in .pod's
	and in the code) is still to be updated!
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (%WHAT2IFD): prefix
	'APP1' erased from values; setter/getter methods changed accordingly.

2005-02-08  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Record.pm (get_description): changed the
	sprintf format string from '%p' to '0x%06x' (really, I did not
	understand what %p was about).

2005-02-07  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment.pm (provide_subdirectory): extended
	to mimick search_record's arguments treatment; this method looks for
	a path of subdirectories from a given record list. All arguments are
	joined to form a path specification, which is followed, and the last
	directory (record list) is returned. An optional last argument may
	specify an initial directory for the search ($this->{records} is the
	defaults). If any subdir entry is not there, it is created on the fly.
	Updated: parse_ifd, parse_makernote, build_IFD_directory_tree.
	* lib/Image/MetaData/JPEG/Segment.pm (process_search_args): this
	private method processes the arguments for search routines, like
	search_record and provide_subdirectory. 1) a start directory is
	chosen by looking at the last argument: if it is an ARRAY ref it
	is popped out and used, otherwise the top-level directory (i.e.,
	$this->{records}) is selected; 2) a $keystring is created by joining
	all remaining arguments on '@', then this string is exploded into
	a @keylist on the same character; 3) the start directory and the
	@keylist is returned.

2005-02-06  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): there is
	now a prediction and correction mechanism for the offsets in the
	interoperability arrays. The simple assumption is that the absolute
	value of offsets can be wrong, but their difference is always right,
	so, if you get the first one right ... a good bet is the address of
	the byte immediately following the next_IFD link. This mechanism is
	currently enabled only for MakerNotes (it might be able to read even
	MakerNotes corrupted by an arbitrary relocation).
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd_children): 
	the code for parsing sub-IFD's was single out into this routine.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_makernote): this
	routine was polished and uncommented; it now deals with every possible
	MakerNote format (because of the catch-all rule), even if sometimes
	it has a minimalist approach ... Information is made available in a
	subdirectory of APP1@IFD@SubIFD, named 'MakerNote_' + the selected
	format (so, there isn't any more any 'MakerNote' entry in IFD0@SubIFD);
	this subdirectory contains all parsed fields plus some "artificial"
	fields like 'ORIGINAL', 'SIGNATURE' and 'ERROR' (an human-readable
	explanation, if a parsing problem occurred).

	* lib/Image/MetaData/JPEG/Tables_makernotes.pl ($HASH_MAKERNOTES): 
	there is now a catch-all rule, a phantomatic binary makernote
	with very broad acceptance rules ... named _Unknown. In this way,
	all MakerNote data areas should be expanded into a subdirectory,
	even if their existence is still unknown.
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_IPTC_dataset): 
	this routine now starts with a size test: we need to have at least
	five bytes if the dataset header is to be read. This makes error
	messages more informative.
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app1_exif): 
	increased the tolerance for thumbnails smaller than declared 
	to 10 (I have now an example of a valid thumbnail which should
	span 6352 bytes, but it spans only 6348 (= -4).

2005-02-05  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm (get_next_marker): an old version
	of "Arles Image Web Page Creator" had a bug which caused the
	application to generate JPEG's with illegal comment segments,
	reportedly due to a bug in the Intel JPEG library the developers
	used at that time (these segments had to 0x00 bytes appended). It
	is true that a JPEG file with garbage between segments is to be
	considered invalid, but some libraries like IJG's try to forgive,
	so we try to forgive too, if the amount of garbage isn't too large ...

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app13): updated
	to dump the eight additional bytes for version 2.5

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app13): adapted
	to check for all identifier in @$APP13_PHOTOSHOP_IDS, and to read
	some additional undocumented bytes (resolution info?) for version
	2.5 only, now saved in a root 'Resolution' record.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (provide_app13_segment): 
	use the first element of @$APP13_PHOTOSHOP_IDS as PhotoShop id
	string, $APP13_PHOTOSHOP_IDENTIFIER is no more.
	(is_app13_ok): just ask $id is found in @$APP13_PHOTOSHOP_IDS.

	* lib/Image/MetaData/JPEG/Tables.pm ($APP13_PHOTOSHOP_IDS): people
	they say this segment always starts with a specific string from
	Adobe, namely "Photoshop 3.0\000". But some old pics, with only
	non-IPTC data, use other strings ..., so now there is an array
	of possible identifier (the first one is considered the default)

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app13): do not
	assume you know the value of the PhotoShop identifier, just read
	it from the record list and complain if you don't find it.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header):
	the endianness is now changed locally, so it is restored when
	this subroutine returns. Previously it was resetting to $BIG_ENDIAN
	in any case, which is an error now that parse_TIFF_header is used
	also during MakerNote parsing. Now, I am using 'local' in all
	places where I used to save and restore the value manually.
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header):
	this method was reworked, taking signature reading away and allowing
	for alternative record directories to save results in. The first
	argument is the start address of the TIFF header; the second one,
	optional, is the record subdirectory where parsed records should
	be saved (defaulting to the root dir). Obvious changes applied to
	parse_makernote(), parse_app1_exif() and parse_app3().

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app1_exif)
	(parse_app3): once parsing is finished, it is better to set the
	segment endianness to undefined, to catch errors. 
2005-02-04  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): same
	thing, for the fifth argument ($offset_ref). Moreover, there is
	no need to pass two offset bases ($tiff_base and $opt_offset_base):
	it is sufficient to pass $offset = $link + $base as second argument
	and only one offset base as secon argument (so, the final optional
	argument is no more).
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header): 
	this method now returns only three arguments; the first one, which
	corresponded to the offset of the first byte immediately after the
	TIFF header, had no use and was therefore dropped.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_makernote):
	complete revision of this method which parses a MakerNote block and
	writes all decoded information to a subdirectory named MakerNote_xxx
	where xxx is a MakerNote format; this subdirectory contains some
	special records: 'ORIGINAL', 'SIGNATURE', 'ENDIANNESS' and 'FORMAT',
	and maybe 'ERROR', if there is some kind of failure. A lot of
	comments added to the code. A bug in the secondary TIFF header
	base was discovered and corrected (this concerns Martin's model!)

	* lib/Image/MetaData/JPEG/Segment.pm: file inclusion is moved at the
	end of the file (there is no need to do this in a BEGIN block). But
	use Tables must use also qw(:Endianness :RecordTypes).

	* lib/Image/MetaData/JPEG.pm: file inclusion is moved at the end
	of the file (there is no need to do this in a BEGIN block).

	* lib/Image/MetaData/JPEG/Tables_makernotes.pl: this new file contains
	most MakerNote-related stuff. Basically, it creates $HASH_MAKERNOTES;
	it MUST always be include by Tables.pm with a "do".
2005-02-03  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): the
	MakerNote records skipped by parse_interop() are analysed here with
	a call to parse_makernote (which shares, however, a large amount of
	pre-processing with recursive calls to parse_ifd).

	* lib/Image/MetaData/JPEG/Tables.pm (%IFD_SUBDIRS): 'APP1@IFD0@SubIFD'
        has now another entry mapping 'MakerNote' to 'MakerNote_'; this
	allows Segment::parse_ifd to process a MakerNote entry as a special
	type of sub-IFD (see also the log entry for parse_ifd).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_interop): this
	method is modified so that it intercepts a MakerNote Interoperability
	array and stores it as one $LONG (instead of many $UNDEF bytes); the
	MakerNote is processed at a later time. The size of the MakerNote
	data area is saved in the extra field.

2005-02-02  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm ($MAKERNOTE_TAG): this new
	variable corresponds to the MakerNote tag (0x927c) which can be
	found in 'APP1@IFD0@SubIFD'; it is exported by :TagsAPP1.

	* lib/Image/MetaData/JPEG/Record.pm (die, warn): explicitely test
	that $this is a reference (it could be the package name, since there
	are "static" methods in this class. Test added to t/JPEG_0_records.t.

2005-02-01  Stefano Bettelli  <bettelli@cpan.org>

        * saved as version 0.13a (documentation is not yet updated from 0.13)

	* COPYING: changed the copyright period from "2004" to "2004,2005"
	for all relevant files in the distribution.

	* t/JPEG_0_records.t: 4 tests added, checking for the implementation
	of the warning/error report system (and the inhibition of warnings).

	* lib/Image/MetaData/JPEG/Record.pm (die, warn): see (die, warn)
	for the main package. Changed files: Record.pm [Record problems
	do not cause warnings, they are all fatal ...]

	* t/JPEG_1_segments.t: 4 tests added, checking for the implementation
	of the warning/error report system (and the inhibition of warnings).

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (sanitise_*): this group of
	routines is now implemented as a group of Segment methods, so that
	it can use the warn/die mechanism of that package. Also, subdir_name
	is now a subroutine, not a subroutine reference. All of these are
	used only by the Segment class, which takes care to intercept errors
	for higher level calls.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (complement_records):
	this function is now a Segment method, so that it can use the
	warn/die mechanism of that package.

	* lib/Image/MetaData/JPEG/Segment.pm (die, warn): see (die, warn)
	for the main package. Changed files: Segment.pm, Segment_parser.pl,
	Segment_dumpers.pl, JPEG_app1_exif,pl

	* t/JPEG_2_rare.t: 4 tests added, checking for the implementation
	of the warning/error report system (and the inhibition of warnings).
	[this is the 700th test milestone!]

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (is_app13_ok): this 
	routine now dies if $what is invalid.

	* lib/Image/MetaData/JPEG.pm (die, warn): these simple methods
	should be used instead of standard "warn" and "die" in this package;
	they print a much more elaborated error message (including a stack
	trace). Warnings can be turned off altogether simply by setting  
	Image::MetaData::JPEG::Backtrace::show_warnings to false. The
	Image::MetaData::JPEG was updated to comply with these rules:
	this included modifications to JPEG.pm, JPEG_comments.pl and
	JPEG_app13.pl (in this file, all sanitise_* subs were moved to the
	JPEG::Segment section). Some error messages were reworked to take
	into account the fact that the subroutine name is already shown in
	the stack trace.
	* lib/Image/MetaData/JPEG/Backtrace.pm ($show_warnings) this
	package variable must be used to inhibit the printing of
	warnings: if it is false, warnings are silently ignored.

	* lib/Image/MetaData/JPEG/Backtrace.pm (backtrace): this is a private
	customisable function (in a separated private package) for creating
	an error (or warning) message with the current stack trace attached.
	It uses additional information returned by the built-in Perl function
	'caller' when it is called from within the 'DB' package (is this
	dangerous?). To be used by JPEG, JPEG::Segment, JPEG::Record ...

2005-01-31  Stefano Bettelli  <bettelli@cpan.org>

	* t/JPEG_2_JPEG_class.t: changed for find_new_app_segment_position;
	also, added twelve new tests to check this method better. 

	* t/JPEG_4_app13.t: changed for find_new_app_segment_position

	* lib/Image/MetaData/JPEG.pm (find_new_app_segment_position): the
	algorithm was reworked to be more sensible: the position is chosen
	immediately before the first (or after the last) element of some
	list, provided that the list is not empty, otherwise the next list
	is taken into account:
	 -) [for COM segments only] try after 'COM' segments;
	       otherwise try after all APP segments;
	 -) [for APPx segments only] try after the last element
	       of the list of APPy's (with y = x..0, in sequence);
	       otherwise try before the first element of the list of
	       APPy's (with y = x+1..15, in sequence);
	 -) try before the first DHP segment
	 -) try before the first SOF segment
	If all these approaches fail, the method returns the position
	immediately after the SOI segment (i.e., 1). The argument must be
	the name of the segment to be inserted (it defaults to 'COM',
	producing a warning).
	(insert_segments): pass the name of the first segment to be
	inserted to find_new_app_segment_position if this is to be called.

	* lib/Image/MetaData/JPEG/TagLists.pod: now starting with:
	=head1 NAME

	Image::MetaData::JPEG::TagLists - This document is an appendix to ...
	so that the POD-to-html translator on search.cpan.org will link
	it correctly. A similar change was applied to the other POD files
	in the JPEG/ directory. Thanks to <search-rt at cpan.org> and in
	particular to Graham Barr for directing me to the problem.

2005-01-16  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment.pm (this is a clarification):
	$this->{parent} links to a parent entity (to which the Segment
	belongs) or is undef (if the Segment does not belong to any entity,
	i.e.,it is an orphan). The parent entity is supposed to know it
	owns the Segment, and a Segment must never be owned by two entities.
	If the link is changed, the old parent must be informed; if it is
	set to a non-undef value, the new parent must be informed as well,
	unless this happens in the ctor.

2004-12-15  Stefano Bettelli  <bettelli@cpan.org>

	* t/JPEG_5_exif_IMAGE.t, t/JPEG_5_exif_IFD.t: added three tests in 
	each file to be extra-sure DateTime is written and re-read correctly.

        * ContentLocationCode, IPTC  /[A-Z]{3}?/ -->  /[A-Z]{3}/

2004-12-06  Stefano Bettelli  <bettelli@cpan.org>

        * saved current version as Image-MetaData-JPEG-0.13, posted to CPAN.
	This is a bug-fixing release; corrections with respect to v.0.12 are:
	--) using 'REPLACE' on an IFD does not erase its sub IFD's;
	--) test of infinities and not-a-number's (more general regexps);
	--) ComponentsConfiguration, FileSource and SceneType records default
	    values are now binary (they were erroneously strings);
	--) standard SubIFD tags now prevail over company-related ones;
	--) FlashEnergy, SpatialFrequencyResponse, FocalPlaneXResolution,
	    FocalPlaneYResolution, FocalPlaneResolutionUnit, ExposureIndex,
	    SensingMethod, CFAPattern can now be set only in SubIFD;   
	--) improvements to documentation
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_interop): 
	the MakerNote hook is commented out, because I need to commit
	a bug-fixing realease. 

	* lib/Image/MetaData/JPEG/MakerNotes.pod: added a discussion on
	the problem of MakerNote corruption in the MakerNote documentation.

	* lib/Image/MetaData/JPEG.pod: added a note about the jhead
	program in the "OTHER PACKAGES" section (why was this missing?)

2004-12-01  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pod: split the documentation into three
	distinct files, because it was becoming too long: JPEG.pod (usage
	and prototypes), JPEG/Structures.pod (general information about the
	structure of JPEG files) and JPEG/TagLists.pod (valid values for 
	various numerical tags). There will be also a JPEG/MakerNotes.pod
	file containing MakerNote discussions only.

2004-11-25  Stefano Bettelli  <bettelli@cpan.org>

        * saved as version 0.12b, sent to users for comments

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data):
	terrible bugs today! Remeber that, even for $action eq REPLACE, we
	cannot delete all the records. We must preserve $REFERENCE records,
	otherwise the corresponding directories would be forgotten; we
	don't want that, for instance, SubIFD is deleted when the records
	of IFD0 are REPLACEd. Tests added to t/JPEG_5_exif_IFD.t. There is
	still a problem: how do we delete (sub)IFD's completely, e.g., the
	GPS IFD? This point must be addressed at a later stage.
	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP1_IFD01_COMPANIES):
	the following company-related fields are now marked as invalid
	because they are present also in the SubIFD section (with different
	numerical values) and I don't want the two entries to collide when
	setting IMAGE_DATA (thanks to Jody Harris for pointing me to the bug).
	Tests added to t/JPEG_5_exif_IMAGE.t
	Record Name                 Tag in SubIFD  Tag in IFD*
	--------------------------  -------------  -----------
	'FlashEnergy'                   0xa20b       0x920b
	'SpatialFrequencyResponse'      0xa20c       0x920c
	'FocalPlaneXResolution'         0xa20e       0x920e
	'FocalPlaneYResolution'         0xa20f       0x920f
	'FocalPlaneResolutionUnit'      0xa210       0x9210
	'ExposureIndex'                 0xa215       0x9215
	'SensingMethod'                 0xa217       0x9217
	'CFAPattern'                    0xa302       0x828e

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): when
	$what is 'IMAGE_DATA', try to insert first into SubIFD, then, into
	IFD0. This favours SubIFD standard tags in front of IFD company-
	related non-standard tags. For security reasons however, these
	non-standard tags are labelled as invalid in Tables.pm: this prevents
	them from being set but not from being recognised if present.

	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP1_SUBIFD_MANDATORY): 
	the 'ComponentsConfiguration' mandatory record was erroneously set
	to '1230', but it is really "\001\002\003\000". Tests corrected.
	A detailed analysis of Tables.pm revealed that the 'FileSource'
	and 'SceneType' records suffered the same problem (also corrected).

2004-11-21  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Record.pm (string_manipulator): the
	reworked string is written in a fixed length field only if the
	string was shortened (this avoids ugly trailing spaces). The
	t/test_photo.desc was updated.

2004-11-20  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_interop): code
	refactoring and clarification. There is now a check that the data
	area of the Interoperability array (for $size's larger than 4)
	exists and has the correct size (this avoids trying to read it if
	the data area offset points out of the segment). Also, if $tag
	corresponds to a MakerNote, and we are in the correct SubIFD, the
	MakerNote parser is called.

2004-11-19  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): new
	flexibility: if $no_next is -1, the "next IFD" link is not even
	read (and so, $$offset_ref advances four bytes less). In this case
	the final test about $no_next never fails. The "next IFD link" is
	sometimes missing in MakerNotes.
        * saved as version 0.12a, sent to Martin for comments
	* t/JPEG_p_podchecker.t: modified the POD tests; it now relies on
	the number of potential syntax problems returned by podchecker()
	instead of relying on the message generated by parse_from_file().

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_makernote): 
	draft method for MakeNote parsing, this time it works better.
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header): 
	there is now a second optional argument, specifying an offset
	pointing to the beginning of the desired TIFF structure, with
	default value 0. In normal Exif APP1 segments it is always zero,
	but this allows for some flexibility explited by MakerNote readers.

2004-11-18  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): the
	reference address for offsets we are going to read is usually the
	TIFF base. But some MakerNotes use a different approach, so a new
	variable ($base) is introuduced allowing for a different base. The
	argument list of parse_ifd is now ($this, $dirnames, $link,
	$tiff_base, $offset_ref, $no_next, $base).	

2004-11-17  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Record.pm (get_description): the textual
	description for a tag not corresponding to a key of %$section_hash
	is now "?? Unknown record ??", not "?? Unknown record type ??";
	moreover, if the corresponding value is not defined the description
	becomes "?? Nameless record ??", not (this is new, and allows for
	more descriptive hashes in Tables.pm). Test files updated.

2004-11-03  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pod: added a link (with L<...>) to the
	ExifTool script and the Image::ExifTool module by Phil Harvey,
	which are now on the CPAN archive.

	* t/JPEG_0_records.t (tests on infinities and not-a-numbers):
	these tests are now implemented as case-insensitive pattern matches,
	because the strings printed for these special IEEE cases are
	system-dependent; e.g., 'inf' can become 'Inf' or 'Infinity' or
	'1.#INF'. I am currently matching against $notnums[$_], where 
	@notnums = (qr/NAN/i, qr/^[^-]*INF/i, qr/-.*INF/i) (note the 'i',
	for case-insensitive match). Thanks to Jost Krieger, cpansmoker
	and the cpan-testers group for help in spotting this bug.

2004-11-02  Stefano Bettelli  <bettelli@cpan.org>

        * saved current version as Image-MetaData-JPEG-0.12, posted to CPAN

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_thumbnail):
	this private method is called by set_Exif_data when the $what
	argument is set to 'THUMBNAIL'. $data must be a reference to a
	scalar value (undefined is an error!). First, we erase all thumbnail
	related records from IFD1 then we reinsert those which are appropriate.
	Last, the update method is called (this also fixes some fields).
	--> $$data eq '': nothing else to do, thumbnail erased.
	--> $$data equal to a JPEG stream: thumbnail data are saved in
	  the root level directory, and a few records are added to IFD1:
	  'JPEGInterchangeFormat' (offset), 'JPEGInterchangeFormatLength',
	  and 'Compression' set to six (this indicates a JPEG thumbnail).
	* lib/Image/MetaData/JPEG.pm (parse_segments): don't claim empty
	files are valid JPEG pictures; in this case, the method dies 
	immediately. Saying what is a valid JPEG file is not easy ...

2004-11-01  Stefano Bettelli  <bettelli@cpan.org>

        * saved as private version 0.11f
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_thumbnail): 
	preliminary implementation of "set thumbnail". This allows to insert
	a JPEG thumbnail or to remove it (uncompressed thumbnails not yet
	supported, and it won't be easy).
        * all save operations in test scripts rewritten so that they use
	in memory variables instead of writing to disk. The only real disk
	access is in t/JPEG_2JPEG_class.t for testing pourposes.
2004-10-30  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): new
	feature. The syntax hash can have a fifth field, acting as a filter.
	Unless it matches the optional $fregex argument, the record is
	rejected. This allows us to exclude some tags from general usage.
	If $fregex is undefined, all tags with a filter are rejected. This
	mechanism is currently used only for the Exif thumbnail.
	(screen_records): match against /^$rule$/s and not /^$rule$/, i.e.,
	use the 's' modifier, forcing the binded scalar to be interpreted
	as a single string (thumbnail data is rejected otherwise ...)
	(remove_app1_Exif_info): if $index is undefined, it defaults to -1.
	So, both (-1) and undef cause all Exif APP1 segments to be removed.

	* lib/Image/MetaData/JPEG.pm (save): it is remarkable that this method
	can write not only to a disk file, but also to a variable in memory.
	A disk file is written if $filename is a scalar with a valid file
	name; memory is instead used if $filename is a scalar reference.
	Documentation updated. Tests added to t/JPEG_2_JPEG_class.t
2004-10-29  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (ordered_record_list):
	this helper function returns an ordered list of records. Records are
	sorted according to the numerical value of their key; if the key is
	not numeric, but its translation matches Idx-n, n is used. If even
	this fails, a stringwise comparison is performed ($REFERENCE records).
	Used only by set_Exif_data().
	* lib/Image/MetaData/JPEG.pod: added an example on how to adjust
	the DateTime record in Exif APP1 IFD0, since this seems very popular

	* lib/Image/MetaData/JPEG/Record.pm (string_manipulator): this new
	routine is used by Record::get_description to format $ASCII and
	$UNDEF values. Unreasonably long strings are trimmed and non-printing
	characters are replaced with their hexadecimal representation. Strings
	are then enclosed between delimiters, and null-terminated $ASCII
	strings have their last character chopped off (but a dot is added
	after the closing delimiter). $ASCII strings use a " as delimiter, 
	while $UNDEF strings use '. Test scripts and files corrected.

	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP1_ROOT_GENERAL): this
	new hash table describes the root directory of an Exif APP1 segment.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): during
	the textual-to-numeric translation stage, apply the translation only
	if the tag, translated with JPEG_lookup, is numeric (before, it was
	applied when the untranslated tag was not numeric). This allows us
	to introduce "translations" for records with textual tags only: the
	translated tag will be of the form "Idx-$n", and $n will be used to
	force an ordering. For instance, ('Identifier', 'Endianness', 
	'Signature', 'ThumbnailData'), in the root directory of an Exif APP1
	segment, are translated to ('Idx-1', 'Idx-2', 'Idx-3', 'Idx-4').

2004-10-28  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header):
	the 'Endianness' record is not an Exif record, so its type is not 
	defined; it was turned to the $UNDEF type, to allow for a syntactical
	rule to be used on it. In general, the difference between $ASCII and
	$UNDEF is meaningful only in true Exif records (the former have a
	terminating null character, the latter correspond to a completely
	free format): one should conform to this prescription at least in
	APP1 and APP3.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app1): this method
	now looks for specific named records with search_record_value, instead
	of relying stupidly on the first record.

2004-10-27  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): added
	a special case for ROOT_DATA: you can only modify the endianness (and
	only to $BIG_ENDIAN or $LITTLE_ENDIAN), everything else is rejected.
	A few tests added to t/JPEG_5_exif_IMAGE.t.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): correction
	for the usual (and here benignous) reference-to-empty-string bug.

	* lib/Image/MetaData/JPEG/Segment.pm (follow_path): no more; the
	functionality of this method is now almost completely in search_record,
	so the code for follow_path could be included in the only two methods
	requiring it: Segment::dump_ifd and JPEG::get_Exif_data.

	* t/JPEG_1_segments.t: a few tests added for Segment::search_record

	* lib/Image/MetaData/JPEG/Segment.pm (search_record): completely new
	design for this method: it searches for a record with a given key in
	a given record directory, returning a reference to the record if the
	search was fruitful, undef otherwise. Search specified as follows:
	  1) a start directory is chosen by looking at the first argument:
	     if it is an ARRAY ref it is popped out and used, otherwise the
	     top-level directory (i.e., $this->{records}) is selected;
	  2) a $keystring is created by joining all remaining arguments on
	     '@', it is exploded into a @keylist on the same character;
	  3) these keys are used for an iterative search starting from the
	     initially chosen directory: all but the last key must correspond
	     to $REFERENCE records. If $key is exactly "FIRST_RECORD" /
	     "LAST_RECORD", the first/last record in the current dir is used.
	The behaviour is now similar to that of the JPEG_lookup function, and
	should spare some lines of code. Trivial modifications in the following
	methods: (Segment methods) follow_path, provide_subdirectory,
	parse_app1_exif, parse_ifd, parse_resource_data_block, dump_com,
	dump_ifd, dump_app13, (JPEG methods) get_comments, get_dimensions,
	get_app0_data, is_app1_Exif, get_Exif_data, build_IFD_directory_tree,
	is_app13_ok, retrieve_app13_subdir, set_app13_data, (test scripts)
	JPEG_1_segments.t, JPEG_4_app13.t, JPEG_5_exif.t.
	(search_record_value): a simple wrapper around search_record(): it
	returns the record value if the search is succesful, undef otherwise.

        * saved as private version 0.11e
	* t/JPEG_5_exif_IMAGE.t: this small test script checks the IMAGE_DATA
	alias for IFD0_DATA and SUBIFD_DATA (supported in JPEG_app1_exif.pl).

2004-10-26  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm: $NATIVE_ENDIANNESS is calcula-
	ted every time and represents the native endianness of the current
	machine. It is exported in the :Endianness group.

	* lib/Image/MetaData/JPEG/Record.pm (check_consistency): updated
	not to fail with floating point numbers (decimal numbers cannot
	always be converted to floating point numbers, so the comparison
	must be limited to, say, six decimal digits). It is now possible
	to set the FovCot tag .....

2004-10-23  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment.pm (set_data): replace \do{''}
	with \(my $ns = "") [thanks to A. Komarnitsky for helping in finding 
	the inconsistency in my previous stupid approach].
	(new): ditto

2004-10-22  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Record.pm
	(decode_integers): was decode()
	(encode_integers): was encode(), see later for this refactoring.
	(decode_floating): this method decodes a data area containing a
	sequence of floating point numbers, correctly taking into account
	the endianness. The type size $n can therefore be only 4, 8 or 12.
	But we cannot support extended double precision on 32-bit machines
	in general! (it is not required for JPEG decoding though)
	(encode_floating): obviously, the reverse of decode_floating. I
	suspect it is buggy and non-portable and a testing headaches.
	(new): the ctor has now the ability to read floating point values.
	(get): the get method has now the ability to encode floating points.
	(get_description): use %g as format string for floating point numbers
	A lot of tests added to check for this floating implementation.
2004-10-21  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_various.pl (get_app0_data): this
	method now returns a reference to a hash with a plain translation
	of the content of the first interesting APP0 segment (this is the
	first 'JFXX' APP0 segment, if present, the first 'JFIF' APP0
	segment otherwise). Segments with errors are excluded. An empty
	hash means that no valid APP0 segment is present.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): ditto
	(multi_level_merge): removed

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (get_app13_data): this method
	now returns data from the first appropriate APP13 segment only (undef
	if no such segment exists). The previous behaviour was inconsistent
	with JPEG::set_*_data, and it brought in more hassle than good. If one
	really has a strange file with more than one APP13 segment, he must
	deal with this strange case by accessing the segments individually.
	Tests and documentation updated.
2004-10-20  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm ($HASH_APP01_IFD0_MANDATORY): 
	there are now two distinct hashes: %$HASH_APP1_IFD0_MANDATORY and
	%$HASH_APP1_IFD0_MANDATORY, possibly differing.
	* t/JPEG_5_exif_IFD1.t: now t/JPEG_5_exif_IFD.t
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): this
	is now a method, and its arguments are ($this, $data, $path); this
	new approach allows for more flexibility while checking for syntactical
	rules (indeed, also for more errors). Moreover, the method now simply
	returns the list ($data_rejected, $data_accepted) [in this order], so
	you still get $data_accepted only in scalar context (but note that the
	order in list context was the opposite before). Changed set_Exif_data
	to take this modification into account.

2004-10-16  Stefano Bettelli  <bettelli@cpan.org>

        * saved as private version 0.11d
	* lib/Image/MetaData/JPEG/Record.pm (check_consistency): this class
	static method receives a number of Record features (key, type and
	count) and a list of values, and tries to build a Record with that
	type and count containing those values. On success, it returns the
	record reference, on failure it returns undef. This subroutine is
	currently used by screen_records in JPEG_app1_exif.pl

2004-10-15  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): 
	new feature: if a record value is a code reference instead of an
	array reference, the corresponding code is executed (passing the
	optional third argument $optional) and the result is stored. This
	is necessary for mandatory records which need to know the current
	segment. This feature is forbidden to the user (currently).

	* lib/Image/MetaData/JPEG/Tables.pm (generate_lookup): this function
	now returns a hash reference. Also, non-exported hashes in Tables.pm
	are now addressed through their references. Also, %HASH_IPTC_GENERAL is
	no more exported (access it with JPEG_lookup{'APP13@__syntax_IPTC'}).

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): moved
	%special_screen_rules's content into Tables.pm, where it belongs to.
	Now, a "super-regular-expression" is no more a special string, but
	a reference to an anonymous routine, stored in Tables.pm, and the
	screen_records method just recognises and executes it.
	The %special_screen_rules hash was a dispatch table for special
	syntax check routines (for those values which are not easy to test
	with a regular expression). These routines had to die if the test
	fails in any way.

2004-10-14  Stefano Bettelli  <bettelli@cpan.org>

	* t/JPEG_5_exif_SubIFD.t: script for set_Exif_data with SUBIFD_DATA

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): adapted
	and tested for SubIFD, including Tables.pm; the %IFD_SUBDIRS hash has
	now some new deep entries, with key equal to '__mandatory', supplying
	mandatory records for a give $what (see set_Exif_data).

	* lib/Image/MetaData/JPEG/Segment.pm (new): the Segment constructor
	now has a new mandatory argument (the first one): a reference to the
	parent entity (a JPEG structure object in general, but it can also
	be undef for "orphan" segments). This reference is currently used to
	get the picture dimensions for the mandatory 'Pixel*Dimension' in the
	Exif SubIFD, but it is going to be needed for other tags in the future.
	Additional files which required modifications: JPEG.pm, JPEG_app13.pl,
	JPEG_app1_exif.pl, JPEG_comments.pl and some test files. Tests added
	to the Segment ctor: it dies if some arguments are invalid.
2004-10-12  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl
	(retrieve_Exif_subdirectories): suppressed

	* lib/Image/MetaData/JPEG/Segment.pm (follow_path): this new
	helper method follows a '@' separated list of dir names and
	returns the final record list (or undef).

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): 
	modified to accept the following values for $what: 
	- ROOT_DATA      APP1               (TIFF header records and similar)
	- IFD0_DATA      APP1@IFD0          (primary image TIFF tags)
	- SUBIFD_DATA    APP1@IFD0@SubIFD   (Exif private tags in IFD0)
	- GPS_DATA       APP1@IFD0@GPS      (GPS data in IFD0)
	- INTEROP_DATA   APP1@IFD0@SubIFD@Interop(erability in IFD0)  
	- IFD1_DATA      APP1@IFD1          (thumbnail TIFF tags)
	- IMAGE_DATA     a merge of IFD0_DATA and SUBIFD_DATA
	- THUMB_DATA     an alias for IFD1_DATA
	- THUMBNAIL      the actual (un-)compressed thumbnail
	- ALL            a structured merge of everything but THUMBNAIL
	A few tests were added to t/JPEG_5_exif.t. Documentation updated.

2004-10-09  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm (%HASH_APP3_SPECIAL/BORDERS) :
	tag names changed to something more "significant" ....
	general reorganisation of these tables, containing tags for IFD0,
	IFD1 and SubIFD, with types, counts, regular expressions and
	support levels for various encodings and sections. Also, added
	some undocumented tags coming from Photoshop >= 7.0 treatment of
	raw camera files (any real reference welcome ...)

2004-10-08  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Record.pm (is_signed): this method now
	returns true or false, instead of 'Y' or 'N' (more intuitive).
	(get_description): bug correction. Integer and rational numbers
	were always printed as signed integers. Now the correct conversion,
	'%u' for unsigned integers and '%d' for signed integers, is applied.
	Test added (this is subtle, because only appears to human beings).
2004-09-30  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): when
	mapping the record list reference, one should make COPIES of the
	array references found in $_->{values}, otherwise the caller could
	use them to corrupt the internal structures. This was a terrible
	bug discovered indirectly by the coverage test. Its solution consists
	simply in replacing $_->{values} with [@{$_->{values}}]. Two tests
	added to t/JPEG_5_exif.t. Two tests also added to t/JPEG_4_app13.t
	for get_app13_data, but it was not affected by the problem.
	(multi_level_merge): this helper function implements the container
	merge necessary to JPEG::get_Exif_dat, and is more robust. Two
	tests added to t/JPEG_2_rare.t to actually test a merge of more
	than two segments.

2004-09-29  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_comments.pl (join_comments): the
	two warnings have been transformed into exceptions.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app1): new checks

	* lib/Image/MetaData/JPEG.pm (open_input): when testing $file_input
	for being a reference, explicitly ask that it is a scalar reference.
	(new): bug corrected, the call to close_input was lacking the
	current object pointer (i.e., $this-> before it). This confirms
	that Perl is not for serious programming.

	* lib/Image/MetaData/JPEG/Segment.pm (update): trying to update a
	segment with errors calls 'die' now, not 'warn'. The same happens
	when trying to update a segment with no update support. Now, there
	is also a check on the number of records: trying to update a segment
	with no records throws an exception (this should catch segments
	created with the 'NOPARSE' flag, which clearly do not own records).
	(new): if the data reference among the arguments of the constructor
	is undefined, we definitely must save a reference to a modifiable
	empty string (like in \do{''}) and not to an unmodifiable one (like
	in \""). This was forbidding the update of initially "empty" segments.
	(set_data): the most robust approach for clearing the current buffer
	is to reset the buffer reference with a reference to a modifiable
	empty string (\ '' is unmodifiable)
	(output_segment_data): if the segment is too long and cannot be
	output, raise an exception (a warning is not effective).

	* beginning test coverage and bug hunting session.
	* t/JPEG_2_JPEG_class.t: the old t/JPEG_1_constructors.t and
	t/JPEG_2_methods.t are now merged in this file, which tries to
	test the Image::MetaData::JPEG class. A new t/JPEG_1_segments.t
	test script tries to test the Image::MetaData::JPEG::Segment class.
2004-09-28  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pm (insert_segment): this method inserts
	a new segment into the current list of segments at position $pos.
	If the segment reference is undefined, the method fails silently.
	If $pos is undefined, the position is chosen automatically (using
	find_new_app_segment_position); if $pos is out of bound, an
	exception is thrown; this happens also if $pos points to the first
	segment and it is SOI. $segref may be a reference to a single
	segment or a reference to a list of segment references; everything
	else throws an exception. If overwrite is defined, it must be the
	number of segments to overwrite during the splice. This method is
	now used in JPEG_comments.pl, JPEG_app13.pl and JPEG_app1_exif.pl.
	Tests added to t/JPEG_2_methods.t. Documentation updated.
	* constructs like $seg = $this->{segments}; @$seg = ... replaced
	with @{$this->{segments}} when not too cumbersome. Same for %$
	* lib/Image/MetaData/JPEG.pm (drop_segments): [thanks to Christopher
	C. Weis for suggesting this feature] this method erases from the
	internal segment list all segments matching the passed $regex
	regular expression. If $regex is undefined or evaluates to the
	empty string, this method throws an exception, because I don't want
	the user to erase the whole file just because he/she did not
	understand what he was doing. The apocalyptic behaviour can be
	forced by setting $regex = ".". As a special case, if $regex ==
	"METADATA", all APP* and COM segments are erased. Documentation
	updated. Tests added to t/JPEG_2_methods.t.
	(drop_segments) is now used inside remove_all_comments,
	remove_app1_Exif_info and remove_app13_info.
2004-09-26  Stefano Bettelli  <bettelli@cpan.org>

	* saved as private version 0.11c

	* lib/Image/MetaData/JPEG/JPEG_various.pl (get_dimensions): bug
	corrected. This routine was not checking that the required records
	were present (they are not there when the segment is not parsed).

	* lib/Image/MetaData/JPEG/Segment.pm (parse): bug corrected.
	If there is no error during this routine, $this->{error} must be
	left undefined; setting it to $@ does not work because it can be ''.
	(parse): the selection of the specific parse routine is now a
	Perl "switch", with a fallback case dispatching to parse_unknown().

	* t/JPEG_2_rare.t: this new test script is meant to catch errors
	in seldom used methods (which is not easy to fit in other test
	scripts), like reparse_as(), get_app0_data(), parse_unknown();
	it was suggested by a coverag test with Devel::Cover. Also added
	a t/test_frankenstein.jpg with examples of some application
	segments not found in the standard t/test_photo.jpg

2004-09-25  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl
	(parse_resource_data_block): bug corrected. The trivial value for a
	data block name in Photoshop APP13 is the empty string ("", length 0),
	not the null character ("\000", length 1). This avoids a lot of 
	stupid <> in the output of Record::get_description.

2004-09-24  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl: almost all methods updated 
	for $APP13_PHOTOSHOP_DIRNAME and its management. This is probably
	not the cleanest solution, but it can do the job for the time being.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app13): updated
	for $APP13_PHOTOSHOP_DIRNAME (also dump_resource_data_block).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl 
	(parse_resource_data_block): updated for $APP13_PHOTOSHOP_DIRNAME

	* lib/Image/MetaData/JPEG/Tables.pm: new $APP13_PHOTOSHOP_DIRNAME
	variable with value 'Photoshop_RECORDS'; this is for supporting
	Photoshop records in a separate directory, in order to make their
	management similar to that of IPTC data. %JPEG_RECORD_NAME modified.

	* t/JPEG_4_app13.t: updated set of tests for Photoshop/IPTC routines.
	Test files are: JPEG_4_app13_IPTC.t, JPEG_4_app13_set.t, JPEG_4_app13.t

	* lib/Image/MetaData/JPEG/Tables.pm (generate_array): new variable
	$APP13_IPTC_DIRNAME = 'IPTC_RECORDS' in Tables.pm in group TagsAPP13.

2004-09-22  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl: all methods in this file
	were changed to reflect the new approach for getting/setting Photoshop
	data; the list of new names is as follows:
	(retrieve_app13_IPTC_segment) --> retrieve_app13_segment(index, what)
	(is_app13_IPTC)               --> is_app13_ok(what)
	(provide_app13_IPTC_segment)  --> provide_app13_segment(what)
	(remove_app13_IPTC_info)      --> remove_app13_info(index, what)
	(get_IPTC_data) ... 2x        --> get_app13_data(type, what)
	(set_IPTC_data) ... 2x        --> set_app13_data(data, action, what)
	many changes in helper rotines and algorithms, too long to explain
	here. Read about the new interface in JPEG.pod.
	* lib/Image/MetaData/JPEG.pod: reorganisation of this man page and
	new sections on getting/setting Photoshop data. This changes the
	previous interface a bit, but, hey, I told you that it could happen!

	* MANIFEST: added a test for the perldoc page based on Pod::Checker
	as t/JPEG_p_podchecker.t (test skipped if the module is not there)

2004-09-20  Stefano Bettelli  <bettelli@cpan.org>

        * tested as version 0.11b

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl 
	(forge_interoperability_IFD): this method takes care to create an
	Interoperability IFD with standard values (dimensions are calculated).
	This should avoid creating gratuitous inconsistencies.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): added
	support for INTEROP_DATA. Tests for this software are collected in
	JPEG_5_exif_INTEROP.t. Documentation updated in JPEG.pod

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_GPS_DATA): this
	method was merged with set_Exif_data after making it more general.
	The generalisation to other data types should now be simpler ....

	* t/JPEG_4b_IPTC.t: renamed to JPEG_4_IPTC_syntax.t
	* t/JPEG_5b_exif.t: renamed to JPEG_5_exif_GPS.t

2004-09-19  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm (JPEG_lookup): corrected a bug
	which was preventing keys evaluating to false from being accepted.
	"unless $key" is not the same as "unless defined $key".

2004-09-18  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (screen_records): 
	This helper function takes a hash reference $data and an IFD path
	specification $path, like 'APP1@IFD0@GPS'. It tries to convert the
	elements of $data into valid records according to the specific
	syntactical rules of the corresponding IFD. It returns a list of
	two hash references: the first list contains the key-recordref
	pairs for successful conversions, the second list the key-value(ref)
	pairs for unsuccessful ones. ... this function extracts and
	generalises the syntax tests which were once in set_GPS_DATA.
	(%special_screen_rules): this hash is a dispatch table for special
	syntax check routines (for those values which are not easily tested
	with a regular expression). I suspect this will grow a lot ...
	(complement_records): another helper routine for inserting records
	into hashes when they are not already present. These routines
	should be used only inside the screen_records function.

	* lib/Image/MetaData/JPEG/Tables.pm (%IFD_SUBDIRS): A sub-hash can
	also have a '__syntax' key, returning a hash of syntactical
	properties to be respected by data in the corresponding IFD. This
	special entry is of course treated differently from the others
	... It was introduced in order to collect in the same place all
	information necessary for setting new data in IFD-like segments. As
	a first result, it avoids the need to export %HASH_GPS_GENERAL. A
	syntactical specification for key $key is now accessed in the
	following way: @{$IFD_SUBDIRS{'APP1@IFD0@GPS'}{__syntax}{$key}};

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (build_IFD_directory_tree):
	This method, obviously, creates a (sub)directory tree in an IFD-like
	segment (i.e. APP1/APP3), and takes care of the "extra" field of the
	newly created directories if mandatory or useful. I really think that
	this "extra" field should be managed differently ....

2004-09-17  Stefano Bettelli  <bettelli@cpan.org>

        * Set all my e-mail addresses in the package to <bettelli@cpan.org>
	* lib/Image/MetaData/JPEG/Tables.pm (%IFD_SUBDIRS): reorganisation
	of this hash, which was not flexible enough; it is now a two-level
	hash, supporting some changes in JPEG_app1_exif.pl. All relevant
	files have been updated (Segment_dumpers.pl, Segment_parsers.pl).

2004-09-15  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG/Tables.pm: corrected a bug slipped in
	at some point during the rewrite of Tables.pm; the following line
        our $THTIFF_LENGTH = JPEG_lookup('APP1@IFD1@StripOffsets'); had to be
	our $THTIFF_LENGTH = JPEG_lookup('APP1@IFD1@StripByteCounts');.
	Since the error was not showing up however, this stuff is probably
	redundant, or I am missing something ...

	* lib/Image/MetaData/JPEG/Tables.pm (JPEG_lookup): this method now
	joins all arguments (references are rejected) on '@', then splits
	the result string on '@' again, in order to be more consistent and
	simpler (?). Calls of JPEG_lookup changed accordingly in Record.pm,
	Segment_parsers.pl, Segment_dumpers.pl, JPEG_app13.pl and

2004-09-04  Stefano Bettelli  <bettelli@cpan.org>

	* lib/Image/MetaData/JPEG.pod: removed the REFERENCES section in
	appendix, and the "references" file from the package. All relevant
	references will be written directly to the perldoc page. Also,
	reworked the Interoperability IFD section a bit.
2004-09-03  Stefano Bettelli  <bettelli@cpan.org>

        * tested as version 0.11a

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): forced an
	ordering on keys during the initial scan; this is necessary because
	the same key can be present twice, in numeric and textual form, and
	we want the corresponding value merging to be stable (numeric keys
	goes first). Same thanks as for the previous bug.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): use
	for (sort keys %IFD_SUBDIRS) ... instead of for (keys %IFD_SUBDIRS),
	so as to fix an undefined ordering in the APP1 IFD0 subdirectories.
	This was causing a lot of problems during "make test". Thanks to
	Andrea Maestrutti, Dan Eble, and the perl.cpan.testers for helping
	correcting this bug.

	* t/JPEG_5_exif.t: changed some stupid "is_deeply" to "is".

2004-08-08  Stefano Bettelli  <bettelli@cpan.org>

        * saved current version as Image-MetaData-JPEG-0.11, posted to CPAN

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data_GPS_DATA): 
	thanks to the previous changes, when creating a new (empty) GPS
	subdirectory, it is not necessary to insert a 'GPSInfo' offset record,
	only the 'GPS' REFERENCE record; if fact, its value would in any case
	be wrong, and it will be calculated automatically at update time.
	We need however to set the "extra" field of this REFERENCE record,
	in order to mimick the case when it is parsed directly from a file.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_TIFF_header): 
	since we decided not to register offset records, the 'IFD0_Pointer'
	record was dropped (i.e., its value is read and used, but it is
	not stored in the main record list). This change is even more
	natural since its value is almost always 8. Trivial doc. changes.

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_ifd): modified
	this method to take changes in parse_ifd into account. There is a
	special treatement for tags holding an IFD offset; these tags are
	regenerated on the fly (since they are no more stored) and their
	value is recalculated and written to the raw data area. This should
	change absolutely nothing in the final file layout.
	(dump_app1_exif): the final call to reparse_as() is no more necessary;
	this was the old warning note: currently, the dump process in Exif
	APP1 recalculates some offsets (IFD links), but does not overwrite
	the parsed records, so that the raw data area and the parsed structure
	are not in sync. Reparsing the segment is a quick fix, but I really
	should update the IFD links' records, or, even better, avoid to write
	these offsets among the records, because they are not interesting
	to the end user.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): this 
	method, after setting up the concerned IFD, searches for deeper
	IFDs with the help of %IFD_SUBDIRS and, if found, parses them
	recursively; for every new subdir, a REFERENCE record is created,
	pointing to it. This method was changed in the following way:
	the originating offset record is removed because it contains very
	fragile information (it should be recalculated every time something
	changes in Exif APP1, for instance, carrying close to zero info);
	moreover, its textual tag is saved in the "extra" field of the
	generated REFERENCE record (just for reference).
2004-08-07  Stefano Bettelli  <bettelli@cpan.org>

	* Saved as PRIVATE version 0.10f

	* lib/Image/MetaData/JPEG/Tables.pm: deeply modified the layout.
	Some variables make now use of JPEG_lookup, instead of declaring
	redundantly other variables. This may be a bit slow, but is cleaner.
	Also, I have declared all private variables with 'my' and all
	exportable ones with 'ours'. Then I have prepared subclasses of
	exportable variables with %EXPORT_TAGS, so that they can be 
	imported selectively by the various modules and files. No variable
	is now exported by default.

	* lib/Image/MetaData/JPEG.pod: trivial change in the section about
	Record objects to document the new JPEG_lookup function. But this
	documentation needs to be revised to report about import rules.
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): updated
	to use JPEG_lookup instead of searching directly %JPEG_RECORD_NAME;
	(set_Exif_data_GPS_DATA): same thing

	* lib/Image/MetaData/JPEG/JPEG_app13.pl: updated the %IPTC_tags
	and %IPTC_names hashes in order to use JPEG_lookup.
	* lib/Image/MetaData/JPEG/Record.pm (get_description): modified
	to use JPEG_lookup instead of searching directly %JPEG_RECORD_NAME.

	* lib/Image/MetaData/JPEG/Record.pm: moved @JPEG_RECORD_TYPE_LENGTH,

	* lib/Image/MetaData/JPEG/Tables.pm (JPEG_lookup): this helper
	function returns record data from the %JPEG_RECORD_NAME hash. The
	argument list is a list of keys for exploring the variuous hash
	levels; e.g., if the list is ('APP1', 'IFD0', 'GPS', 0x1e), the
	selected value is $JPEG_RECORD_NAME{APP1}{IFD0}{GPS}{0x1e}.
	If, at some point during the search, an argument fails (it is not
	a valid key) or it is not defined, the search is interrupted, and
	undef is returned. Note also that the return value can be a string
	or a hash reference, depending on the hash search depth. If the key
	lookup for the last argument fails, a reverse lookup is run (i.e.,
	the key corresponding to the value equal to the last user argument
	is searched). If even this lookup fails, undef is returned.

2004-08-06  Stefano Bettelli  <bettelli@cpan.org>

	* Saved as PRIVATE version 0.10e

	* lib/Image/MetaData/JPEG.pod: added a section about changing Exif
	data (which currently is limited to GPS data), and a very extensive
	appendix about valid records for Exif APP1, which will be used as
	a line guide for the future Exfi setters.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data_GPS_DATA): 
	this method implements the setter of Exif GPS data; it includes a
	lot of format checks and it is moderately simple, since GPS tags
	are not too complicated. A lot of tests added to check GPS data
	syntax. Documentation updated (so, read there ...)
	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (set_Exif_data): entry
	point for setters of Exif APP1 data. It works a hash reference $data,
	$what in /GPS_DATA|...todo/ and $action in /ADD|UPDATE|SET/, but this
	interface might not be "official".
	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app1_exif): added
	a reparse_as at the end of this method; currently, the dump process
	in Exif APP1 recalculates some offsets (IFD links), but does not
	overwrite the parsed records, so that the raw data area and the
	parsed structure are not in sync. Reparsing the segment is a quick
	fix, but I really should update the IFD links' records, or, even
	better, avoid to write these offsets among the records, because they
	are not interesting to the end user.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): check
	added; this method returns immediately (with undef) if the current
	Segment is not an Exif APP1 Segment.

	* lib/Image/MetaData/JPEG/Record.pm (get_description): C-strings,
	i.e., null-terminated strings, have now the last null character
	chopped off, but a '.' is written after the closing '"'. This 
	should make the output more readable.
2004-08-05  Stefano Bettelli  <bettelli@localhost>

	* Saved as PRIVATE version 0.10d

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): updated
	the Structure-level method to deal with the different data types
	returned by the Segment-level method. Tests added.

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl (get_Exif_data): added
	a second argument ($what) controlling the subset of Exif records
	returned by this method (this is far too long to explain here,
	read the documentation for this). Summarising:
	- ALL          (all Exif and preamble records)    ref to hash of hashes
	- IMAGE_DATA   IFD0 + IFD0@SubIFD  (primary image)   ref to hash
	- THUMB_DATA   IFD1                (thumbnail image) ref to hash
	- GPS_DATA     IFD0@GPS            (GPS data)        ref to hash
	- INTEROP_DATA IFD0@SubIFD@Interop (interoperabilty) ref to hash
	- THUMBNAIL    (the thumbnail data area in APP1)     ref to scalar
	Tests added. Documentation updated. This approach should be much
	more user-friendly and looks like the definitive interface I want
	to use for inquiring Exif data.
2004-08-04  Stefano Bettelli  <bettelli@localhost>

	* Saved as PRIVATE version 0.10c

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): corrected
	a silent bug: when testing for the presence of the RecordVersion
	tag, don't just check that there is an entry in the hash, but also
	check that the array pointed to by this hash is not empty.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): a new
	functionality added to the "setter". The $action argument can be:
	- ADD : new records are added and nothing is deleted; however, if
	  you try to add a non-repeatable record which is already present,
	  the newly supplied value replaces the pre-existing value.
	- UPDATE : new records replace those with the same tags, but the others
	  are preserved. This makes it possible to modify repeatable records.
	- REPLACE : all records present in the IPTC subdirectory are deleted
	  before inserting the new ones.
	So, 'ADD' and 'REPLACE' are as before, while 'UPDATE' is new and
	allows for selective replacement of some tags. The default remains
	'REPLACE'. Documentation updated. Tests added and updated.

2004-08-03  Stefano Bettelli  <bettelli@localhost>
	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app2_ICC_tags):
 	updated to reflect the changes in Record::get_size.

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_interop):
	updated to reflect the changes in Record::get_size.

	* lib/Image/MetaData/JPEG/Segment.pm (create_record): $count means
	now "length" if the record type is variable-length and the data area
	is specified through an offset (but I think this never happens).

	* lib/Image/MetaData/JPEG/Record.pm (new): according to the new
	meaning of "count" in the Record class, the argument $count in the
	constructor changes like this: if the type is fixed-length, $count
	is mandatory and must correspond to the number of values to be
	read from the passed scalar; if the type is variable-length, $count
	is optional (if specified, it is a counter-check; it must correspond
	to the size of the passed scalar).

	* lib/Image/MetaData/JPEG/Record.pm: some useless incoherences
	eliminated (dangerous?): the type length in @JPEG_RECORD_TYPE_LENGTH
	for non-numeric types (currently ASCII strings, UNDEF strings and
	Perl references) is set to zero; it is meant with this that the type
	length is variable, and all sizes should be accepted. This implicitely
	changes Record::get_size to return 0 also for ASCII and UNDEF.
2004-08-01  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/JPEG_app1_exif.pl: changed JPEG_exif.pl
	to JPEG_app1_exif.pl, for uniformity with JPEG_app13.pl

	* lib/Image/MetaData/JPEG.pod: re-checked and clarified the part
	of the documentation concerning IPTC data management, including
	all previous changes and a note on what is translated when 
	'TEXTUAL' is on (tags, i.e, keys, not the values).

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): reworked
	this method. Added a new logic for $action == 'ADD': old values
	are merged to new ones; if this leads to the violation of a non
	repeatability constraint, only the new value is retained (this is
	done by the new helper function shift_non_repeatables). Added
	a new logic to make sure that a 'RecordVersion' record is always
	present. Updated all IPTC tests relevant to 'set'.

	* lib/Image/MetaData/JPEG/Tables.pm: corrected a bug in the 'word',
	'line' and 'paragraph' regular expression for IPTC data (they were
	accepting an arbitrary prefix or suffix). Corrected and updated
	the appropriate tests in t/JPEG_4b_IPTC.t.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (get_IPTC_data): do not
	delete the 'RecordVersion' record from the returned hash. I do
	not know if this is the right choice, but the previous behaviour
	was not documented either. Added a test for this.

2004-07-19  Stefano Bettelli  <bettelli@localhost>

	* Saved as PRIVATE version 0.10b

	* lib/Image/MetaData/JPEG.pm (get_segments): the passed regular
	expression is now changed to "." if undefined or set to the empty
	string (thus returning all segments or all indexes). I do this
	because I want to avoid the stupid behaviour of m//:
	from `man perlop`: if the pattern evaluates to the empty string,
	the last successfully matched regular expression is used instead;
	if no match has previously succeeded, this will (silently) act
	instead as a genuine empty pattern. Added two tests against this.
	* lib/Image/MetaData/JPEG/JPEG_exif.pl (is_app1_Exif): bug corrected;
	this was crashing when presented an APP1 segment without a record
	called 'Identifier' (this happens for XML APP1 segments ....)

2004-07-18  Stefano Bettelli  <bettelli@localhost>

	* t/test_photo.jpg, t/test_photo.desc: reduced the test image size,
	this cuts down its weight from ~ 200KB to only 33KB.
	* lib/Image/MetaData/JPEG.pm (save): added binmode for file open
	calls (it turned out that on Windows it really makes a difference,
	also when writing). Thanks to Andrea Maestrutti for help with this bug.

	* lib/Image/MetaData/JPEG/Segment.pm (show_directory)
	(Directory_Banner): added protections against invalid
	references among function arguments. Mark invalid references.

	* lib/Image/MetaData/JPEG/Segment.pm (get_description): chomp
	is run only if $this->{error} is defined (avoid error situations).

2004-07-16  Stefano Bettelli  <bettelli@localhost>

	* t/JPEG_1_constructors.t, t/JPEG_2_methods.t: added binmode for
	file open calls (it turned out that on Windows it really makes a
	difference!). Thanks to Andrea Maestrutti for help with this bug.

	* t/JPEG_0_records.t: added (it had been left out from the module
	submitted to CPAN because it was not listed in MANIFEST).
2004-07-13  Stefano Bettelli  <bettelli@localhost>

        * saved current version as Image-MetaData-JPEG-0.10, posted to CPAN
	* lib/Image/MetaData/JPEG.pod: documentation updated. IPTC info
	largely rewritten. Exif info introduced. New appendices.

	* lib/Image/MetaData/JPEG/Segment.pm (output_segment_data): added
	a debugging check on the maximum size for a segment.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): substantial
	modification of this methods (many more checks). It now accepts IPTC
	data in various formats and updates the IPTC subdirectory in the
	segment. The key type of each entry in the input %$data hash can be
	numeric or textual, independently of the others (the same key can
	appear in both forms, the corresponding values will be appended).
	The value of each entry can be an array reference or a scalar (you
	can use this as a shortcut for value arrays with only one value).
	The $action argument can be 'ADD' or 'REPLACE', and it discriminates
	weather the passed data must be added to or must replace the current
	datasets in the IPTC subdir. The return value is a reference to a
	hash containing the rejected key-values entries. The entries of %$data
	are not modified. An entry in in the %$data hash can be rejected
	for various reasons:
	  - the tag is textual or numeric and it is not known;
	  - the tag is numeric and not in the range 0-255;
	  - the entry value is an empty array;
	  - the non-repeatable property is violated;
	  - the tag is marked as invalid;
	  - the length of a value is invalid;
	  - a value does not match its mandatory regular expr.
	This is a major improvement on the formerly unattended user input.
	There is not a similar check on data already written in the file,
	because it is not clear what one should do in presence of "errors".

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (value_is_OK): this private
	function is able to test wether a given array of values fits with
	a given IPTC tag. Info is taken from %HASH_IPTC_GENERAL. It is
	called only by set_IPTC_data.

	* lib/Image/MetaData/JPEG.pm (find_new_app_segment_position): added
	a check, just in order to avoid a warning for half-read files with
	an incomplete set of segments; no "position" is returned past the
	segment array end (i.e. not smaller than scalar get_segments()).
	Added a test against this case.

2004-07-12  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (get_IPTC_data): changed
	the behaviour of this method, which is now a generalisation of
	the method with the same name in the Segment class, not only an
	interface to. First, all IPTC APP13 segment are retrieved (if
	none is present, the undefined value is returned). Then,
	get_IPTC_data is called on each of these segments, passing the
	argument ($type) through. The results are then merged in a single
	hash and a reference to it is returned.

	* lib/Image/MetaData/JPEG.pod: added a reference section as an
	appendix specifying the set of valid IPTC tags for APP13, as
	well as the additional constraints on their values. The same
	information is now available in %HASH_IPTC_GENERAL in Tables.pm

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (get_IPTC_data,set_IPTC_data): 
	removed the "XML" option, since it was really only poorly implemented
	in the getter; it will be reinstated only when and if there is a
	real need for this. Modified the perldoc page accordingly.
2004-07-11  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/JPEG_exif.pl (retrieve_app1_Exif_segment): 
	(provide_app1_Exif_segment, remove_app1_Exif_info, get_Exif_data)
	(set_Exif_data, [Segment]is_app1_Exif, retrieve_Exif_subdirectories)
	(get_Exif_data) new methods very similar to APP13 IPTC high level
	functions. They implement, of course, the "read" part of Exif APP1
	segments. The get_Exif_data method returns a reference to a hash
	containing a named (the tag) hash references. Each sub-hash contains
	a copy of all Exif tags/values present in a particular IFD (sub)di-
	rectory (including a special root directory containing some tags
	and the links to IFD0 and IFD1). As usual, the output format can
	be "NUMERIC" or "TEXTUAL". An example of the returned reference is:

	{ APP1                     => { Endianness => [ "II" ], ... },
	  APP1@IFD0                => { Model => [ "KODAK DX3900" ], ... },
	  APP1@IFD0@SubIFD         => { FocalLength => [117, 10], ... },
	  APP1@IFD0@SubIFD@Interop => { InteroperabilityIndex => ["R98"], ...},
	  APP1@IFD1                => { XResolution => [72, 1], ... }
	* lib/Image/MetaData/JPEG/JPEG_app13.pl (set_IPTC_data): added an
	explicit protection against an undefined value for the first argument

2004-07-10  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (remove_app13_IPTC_info): 
	this new method eliminates all traces of IPTC information from
	the $index-th APP13 IPTC segment. If, after this, the segment is
	empty, it is eliminated from the list of segments in the file.
	If $index is (-1), all APP13 IPTC segments are affected at once.
	Added some tests for this in JPEG_4_iptc.t
2004-07-10  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/Segment_dumpers.pl (dump_app1),
	(dump_app1_exif, dump_TIFF_header, dump_ifd): implemented a set of
	routines for dumping an Exif APP1 segment to disk. The thumbnail
	size is checked for consistency. All records within an IFD are
	ordere according to their tags. There is no unused space in the
	dump, so just calling update() on an Exif APP1 segment even without
	modifying its content can give you a smaller file (some tens of
	kilobytes can be saved). Checked it works on all my pictures.

2004-07-09  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/Record.pm (encode, decode): corrected
	various bugs for signed types and nibbles. Logic rewritten. The
	directive "use integer" was abandoned, since it limits integers
	to signed 32-bits (while we need at least unsigned 32-bits). The
	performance drop is probably negligible if the computer has a
	math coprocessor. Written a comprehensive test suite for the
	Record class (t/JPEG_0_records.t).
	* lib/Image/MetaData/JPEG/Segment.pm (set_data): this method now
	accepts a reference or a scalar as first argument, and treats it
	accordingly (this avoids copying in some contexts).

2004-07-08  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_app1_exif,
	parse_app3): adapted to the new parse_ifd style. These routines
	look now much simpler (although they are a bit less flexible).

	* lib/Image/MetaData/JPEG/Segment_parsers.pl (parse_ifd): this
	method takes now care to parse the subdirectories of a given IFD
	on its own (using the %IFD_SUBDIRS lookup table). The new argument
	list is ($this, $dirnames, $link, $tiff_base, $offset_ref, $no_next),
	i.e. $tiff_base is a value, not a ref, and @vip_tags is no more.

	* lib/Image/MetaData/JPEG/Tables.pm (%IFD_SUBDIRS): this new enum
	is intended to automatise the parsing of subdirectories of IFDs
	in APP1 and APP3 (needed also for dumping I think).

	* lib/Image/MetaData/JPEG/Segment.pm (set_data): let this method
	return the size of appended data.

	* lib/Image/MetaData/JPEG/Record.pm (encode): corrected two bugs
	on this untested method (overwriting $_ in an internal loop and
	not getting the endianness right).

2004-07-07  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaData/JPEG/Segment.pm (update): dispatch to 
	dump_app1 if necessary (new methods in Segment_dumpers.pl).

	* lib/Image/MetaData/JPEG/Segment.pm (output_segment_data): fixed
	a bug in this method for zero-length comments. In fact, the data
	area of a segment can be void and, nonetheless, the segment might
	require a segment length word; in practise, the only segments not
	needing the length word are SOI, EOI and RST*. Test added.

	* lib/Image/MetaData/JPEG/JPEG_app13.pl (get_IPTC_data): when the
	option is 'TEXTUAL' (i.e., use textual instead of numerical tags),
	if a numerical IPTC tag is not known, a custom textual tag is
	created with "Unknown_tag_" followed by the numerical value (this
	solves a bug with non-standard tags). What to do for set_IPTC_data?

	* Renamed Image::MetaInfo::JPEG to Image::MetaData::JPEG.

2004-06-25  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.09

	* lib/Image/MetaInfo/JPEG.pod: documentation updates, including
	a new introductory section on JPEG files and APP0.

	* lib/Image/MetaInfo/JPEG/JPEG_app13.pl (provide_IPTC_subdirectory): 
	corrected another bug here, thanks to testing.
	* lib/Image/MetaInfo/JPEG/Segment.pm (update): simplified test

	* lib/Image/MetaInfo/JPEG.pm (find_new_app_segment_position): bug:
	if there is a DHP(SOF) segment, return its position, not the
	position immediately after (because we are replacing there!)

	* lib/Image/MetaInfo/JPEG.pm (parse_segments): don't have dataless
	segments saved in any case (setting $flag equal to undef for them
	was a bug! the logic is now a bit different).

	* lib/Image/MetaInfo/JPEG.pm (new): this really returns undef when
	no error is set now (first "bug" catched with package testing!).

	* t/JPEG_1_constructors.t: initial test set for JPEG ctors
	* t/JPEG_2_methods:        initial test set for JPEG methods
	* t/JPEG_3_comments:       initial test set for comment routines
	* t/JPEG_4_IPTC:           initial test set for IPTC routines
	there is also a test photo in t/ using ~ 200Kb.
2004-06-24  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG.pm (save): changed to fail immediately
	if the "read_only" member is set (currently, only if the JPEG
	object is opened with the "FASTREADONLY" option).

	* lib/Image/MetaInfo/JPEG.pm (new): there is now a third optional
	argument, $options. If it matches the string "FASTREADONLY", only
	those segments matching $regex are actually stored; also, everything
	which is found after a Start Of Scan is completely neglected. This
	allows for very large speed-ups, but, obviously, you cannot rebuild
	the file afterwards, so this is only for getting information fast,
	e.g., when doing a directory scan.

	* lib/Image/MetaInfo/JPEG.pm (parse_segments, get_next_marker)
	(parse_ecs): updated to take the $this->{read_only} field into
	account. The new approach is the following: in general, all segments
	are read, saved and parsed if possible. If there is a regular
	expression argument to the ctor matching only a few segment names,
	only those segments are parsed (they are nonetheless saved). If
	$this->{read_only} is set (see FASTREADONLY later), the segments
	not selected for parsing are not even read and saved; moreover,
	everything after the SOS segment is neglected (this is for fast
	information retrieval).

	* lib/Image/MetaInfo/JPEG.pm (get_data): this method returns a
	portion of the input file (specified by $offset and $length). It is
	necessary to mask how data reading is actually implemented. As usual,
	it dies on errors (but this is trapped in the constructor). This
	method returns a scalar reference; if $offset is just "LENGTH", the
	input length is returned instead.

	* lib/Image/MetaInfo/JPEG.pm (open_input): this method, replacing
	"slurp_buffer", takes care to open a file handle pointing to the
	JPEG object specified by $file_input. If the "file name" is a
	scalar reference instead, it is saved in the "handle" member (and
	it must be treated accordingly in the following). Nothing is
	actually read now, only the handle is stored; this is needed for
	FASTREADONLY, see later. There is also a very short close_input().

2004-06-19  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.08

	* lib/Image/MetaInfo/JPEG.pod: documentation update, including
	the description of a few "internals", to allow the curious user
	to access directly the result of the segments' parsing.

	* lib/Image/MetaInfo/JPEG.pm (find_new_app_segment_position): 
	this algorithm was changed. Now, if a DHP segment is present,
	the method returns the position immediately before the first DHP
	segment; otherwise, it tries the same with SOF segments; otherwise,
	it selects the position immediately after the last application
	or comment segment. If even this fails, it returns the position
	immediately after the SOI segment (i.e., 1).
2004-06-18  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/JPEG_various.pl (get_app0_data): 
	this method returns a reference to a hash with the content of
	the APP0 segments (a plain translation of the segment content).
	Segments with errors are excluded. Note that some keys may be
	overwritten by the values of the last segment, and that an empty
	hash means that no valid APP0 segment is present.
	* lib/Image/MetaInfo/JPEG/JPEG_various.pl (get_dimensions): 
	revised and commented. This method and get_description() are
	now in a separate file (JPEG_various.pl).
	* lib/Image/MetaInfo/JPEG/JPEG_app13.pl (JPEG::set_IPTC_data): 
	analogous to JPEG::get_IPTC_data; however, the segment is created
	and initialised with provide_app13_IPTC_segment if it is not
	there, so the segment retrieval should not fail.
	* lib/Image/MetaInfo/JPEG/JPEG_app13.pl (JPEG::get_IPTC_data):
	this method is an interface to the method with the same name
	in the Segment class. First, the first IPTC APP13 segment is
	retrieved (if there is no such segment, the undefined value is
	returned). Then the get_IPTC_data is called on this segment
	passing the argument through.

2004-06-17  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG.pm (get_next_marker, parse_segments,
	parse_ecs): changed to work on in-memory buffers. This almost
	halves the system read time, but strangely increases the user
	run time, so there must be something I don't understand here.
	Note: ~40-55% processing time is spent in only two methods:
	slurp_buffer and parse_ecs (after a few optimisations).
	* lib/Image/MetaInfo/JPEG.pm (new): the member storing a file
	handle is gone, but we have now a member storing a reference to 
	the JPEG stream. The first argument of the ctor is the JPEG
	stream. The ctor saves the file stream as a private object,
	then it parses it and stores its sections internally. The stream
	can be specified in two ways: [a scalar] interpreted as a file
	name to be opened and read; [a scalar reference] interpreted as
	a pointer to an in-memory buffer containing a JPEG stream.
	This interface is similar to that of Image::Info, but no open
	file handle is accepted.

	* lib/Image/MetaInfo/JPEG.pm (slurp_buffer): this method replaces
	the old check_file. It accepts just one argument: if it is a
	reference, it is assumed to point to a JPEG stream and saved
	internally; if it is a scalar, it is interpreted as a file name
	whose content is to be read into memory and treated as before.
	No test on SOI is performed.

2004-06-15  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/Record.pm (get_description): non
	printable characters are now replaced with "\" followed by
	a two digit hexadecimal representation (it is shorter than
	a three digit octal representation!).

	* Makefile.PL: arghh ... there was a "use 5.008004" also here!

	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_makernote): 
	this new method is the entry point for parsing maker notes.
	It should be easy to extend it to all maker notes whose
	structure follows that of a regular IFD.
	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_app1_exif): 
	if a Maker Note tag is found in the Exif SubIFD, then we should
	try to decode it. This is likely to fail, because most vendors do
	not publish their MakerNote format. However, if the note is
	decoded, the findings are written in a new subdirectory (currently
	I think it is wiser not to delete the unparsed MakerNote record).
	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_app1_exif): 
	the "garbage" field in APP1 Exif and APP3 was removed, because
	it makes no sense (the IFDs structure is way more complicated
	than I though)!
2004-06-13  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/Segment.pm (reparse_as): this new method
	re-executes the parsing of a segment after changing the segment
	nature (well, its name). This is very handy if you have a JPEG file
	with a correct application segment exception made for its name. I
	used it the first time for a file having an ICC_profile segment
	 (usually in APP2) stored as APP13. Note that the name of the
	segment is permanently changed, so, if the file is rewritten to
	disk, it will be "correct".

	* lib/Image/MetaInfo/JPEG/Segment.pm (parse): this new method
	contains the parse code once written inside the segment ctor.
	This allows the parsing to be rerun (the error message and the
	old parsed records are flushed at the beginning).

2004-06-12  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_app2_ICC_tags) &
	(parse_app2_ICC_profiles): these new methods implement the parsing
	of APP2 ICC profiles (there is a subdirectory for the profile
	header and another subdirectory for the tag table). In Tables.pm
	there is a new hash table named %HASH_APP2_ICC.

	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_app2_flashpix):
	This method parses an APP2 Flashpix extension segment, and is not
	really reliable, since I have only one example and very badly
	written documentation. Moreover, I think that the FPXR format is
	the worst format I have ever seen.
	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_app2): this
	new method is the entry point for parsing APP2 segments.

	* lib/Image/MetaInfo/JPEG/Segment_parsers.pl (parse_TIFF_header):
	the identifier length is now taken from $good_identifier, while
	before it was fixed to 6 bytes. A similar approach in parse_app1().

2004-06-12  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.07

	* lib/Image/MetaInfo/JPEG.pod (Image): Documentation update

	* lib/Image/MetaInfo/JPEG.pm (parse_segments): initialise
	$segments only once, at the beginning.

2004-06-10  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/Record.pm: I gave up trying to calculate
	the length of a Perl reference. This is probably allocation and
	implementation dependent; so I use zero and change the logic 
	where its length is used. This required trivial changes only in
	Record::new and Record::get_size (all other routines are unaffected
	so far, but this is a potential risk for the future ....)

2004-06-09  Stefano Bettelli  <bettelli@localhost>

        * The Image::MetaInfo::JPEG::Structure class is no more; it is
	now called simply Image::MetaInfo::JPEG (this is the package
	name). So, JPEG.pm and JPEG/Structure.pm were merged in
	lib/Image/MetaInfo/JPEG.pm, the documentation file moved
	lib/Image/MetaInfo/JPEG.pod and all other library files left
	in lib/Image/MetaInfo/JPEG/. The change was otherwise trivial.
	* lib/Image/MetaInfo/JPEG.pm: commented "use 5.008004" out.
	I don't really know the Perl version requirements; maybe just
	Perl 5 is sufficient, but I don't know how to test it.

2004-06-07  Stefano Bettelli  <bettelli@localhost>

	* lib/Image/MetaInfo/JPEG/Structure.pm (new): There is now a second
	argument, $regex. This string is matched against segment names, and
	only those segments with a positive match are parsed. This allows
	for some speed-up if you just need partial information. For
	instance, if you just want to manipulate the comments, you could
	use $regex equal to "COM". If $regex is undefined, all segments are
	parsed. This required a change also in Structure::parse_segments.
	Remember that SOS segments are needed for get_dimensions().

	* lib/Image/MetaInfo/JPEG/Segment.pm (new): there is now an
	optional third argument for the constructor, a flag. If this
	flag matches "NOPARSE", no parse routine is run in the segment
	constructor (this can be done by generating an informative error).
	This probably allows for some speed-up if we don't need the
	information stored in the segment.
	* lib/Image/MetaInfo/JPEG/Structure_comments.pl (split_comment_string):
	corrected a terrible bug: $max_length is 2**16-3, not 2**16-2 !!!

	* lib/Image/MetaInfo/JPEG/Segment.pm (set_data): this new method
	appends (or overwrites, if the second argument is "OVERWRITE")
	a string to the current segment data area. This hides the
	details of how the data area itself is implemented. The only 
	four methods knowing explicitely about Segment::dataref should
	now be new, size, data and set_data.
	* lib/Image/MetaInfo/JPEG/Segment.pm (output_segment_data): this
	new method replaces the old get_segment_data. It needs one argument
	more, a file handler, and it prints directly into it instead of
	returning a string; it returns the 1/0 in case the write succeeded/
	failed. Structure::save() needed an obvious update.

	* lib/Image/MetaInfo/JPEG/Segment.pm (new): the second argument
	to a "new Segment" call is now a reference to a memory area, not
	directly a scalar, and it is saved in Segment::dataref, which
	replaces Segment::data. This makes passing a third argument clearer.
	Some trivial changes were needed in the Segment class (mostly
	transparent, since the access is mediated by Segment::data())
	and in the routines calling the Segment constructor (that is,
	in Structure.pm, Structure_app13.pl and Structure_comments.pl).

2004-06-07  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.06

	* lib/Image/MetaInfo/JPEG.pm: prepared an initial POD file.
	This file is going to be the "official" documentation.

2004-06-06  Stefano Bettelli  <bettelli@localhost>

        * miserably replacing all occurrences of "retrive" with
	"retrieve" \Re*trieve"\ (thanks to my wife).
	* COPYING: added a copyright notice to the beginning of this file.
	A shorter (3 lines) notice is present at the beginning of all files
	in lib. Maybe this will not be the final license scheme. See also
	the LICENSE files for license terms. 

	* MANIFEST: initial setup for a CPAN release, following the
	lines of "man perlnewmod". However, this still needs a lot of
	testing, so the package is still "private".

2004-06-04  Stefano Bettelli  <bettelli@localhost>
	* Structure_comments.pl (join_comments): this method now calls
	set_comment with the new behaviour, so it is safe against a
	very long joint comment.

	* Structure_comments.pl (set_comment): this method now replaces
	the $index-th comment segment with one or more new segments
	based on the user string. If the string is too big, it is broken
	down and multiple segments are created. If the string is undef,
	the comment segment is erased. If $index is out-of-bound, only a
	warning is printed. This mimics the new behaviour of add_comment.

	* Structure_comments.pl (add_comment): in case the passed string
	is too big (there is a 64KB limit in JPEG segments), it is broken
	down in smaller strings and multiple "Comment" segments are
	inserted in the file (they are contiguous). This replaces the
	previous behaviour of issuing a warning and trimming the string.

	* Structure_comments.pl (split_comment_string): this new method
	splits a string into chunks which can fit in a comment segment.
	Note that "" maps to (""), while an undefined value maps to ().
	So, it is possible to specify an empty comment, and it is different
	from specifying an undefined comment. The comment_trim_string
	method is no longer necessary (removed).
	* Segment.pm (Directory_Banner): simplified the string join
	and eliminated the string "Block " in the banner.

2004-06-01  Stefano Bettelli  <bettelli@localhost>

	* Segment_parsers.pl (parse_app3, parse_app1_exif, parse_ifd): 
	code refactoring (some functionalities moved inside parse_ifd).
	This should make APP3 and APP1 parsing more readable.
2004-05-30  Stefano Bettelli  <bettelli@localhost>

	* Stupid changes using the comma operator in Segment.pm, Record.pm.

2004-05-29  Stefano Bettelli  <bettelli@localhost>

	* Segment_parsers.pl (parse_app12): the interpretation of the
	first line is now less ambitious, the line is simply saved in
	one ASCII field, named MakerInfo (it can contain null characters
	though). This prevents untold errors for APP12 segments whose
	format is really unknown (to me). I am still looking for docs.

	* Segment_parsers.pl (parse_ifd): I used to complain in case no
	entry was present in the currently analysed IFD, but it turned
	out this is only annoying; so, the warning was removed.

	* Structure.pm (save): modified the method description, to
	make it clear that "high level" methods (those implemented
	in the Structure_<segment name>.pl files) take care of calling
	update(), when needed, on their own. So, a user of the library
	should not care about calling update().

	* Structure_comments.pl (join_comments): this method accepts now
	two arguments: ($separation, @selection). The first string is used
	between every two concatenated strings (it defaults to a newline,
	i.e., "\n"). The second argument is the old single argument.
	$separation is used as first argument of a join() call.

2004-05-05  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.0.5
	* Structure.pm (save): This method writes the data area of each
	segment in the current object to a disk file. If the filename
	is undef, it defaults to the file originally used to create this
	Structure object. This method returns "true" (1) if it works,
	"false" (undef) otherwise.
	* Structure_app13.pl (get_IPTC_data): implemented a rough XML
	translation for IPTC data. However, it would be more consistent
	to implement something on the lines of parse_app1_xmp().

2004-05-03  Stefano Bettelli  <bettelli@localhost>

	* Structure_app13.pl: this file contains a number of utilities
	for managing IPTC data without dealing with the details of the
	low level representation (although sometimes this means taking
	some decisions for the end user ....). The new methods are:
	  Segment::set_IPTC_data($data, $action);
	* Structure.pm (get_segment): replaces get_segment_indexes. It
	returns segment references, not their indexes. However, the
	previous behaviour is restored if the second argument is "INDEXES".
	This requires some adjustments in the comment utilities file.

	* Structure_comments.pl (add_comment): no need to call update
	at the end of this routine, thus removed.

	* Structure.pm (find_new_app_segment_position): this new Structure
	method finds a position for a new application or comment segment
	to be placed in the file. If a SOS segment is present, it returns
	the position immediately before it; otherwise, it selects the
	position immediately after the last application or comment segment.
	If even this fails, it returns the position immediately after the
	SOI segment (i.e., 1). This affects also Structure::add_comment().

2004-05-02  Stefano Bettelli  <bettelli@localhost>

	* Record.pm (get_description) and Segment.pm (show_directory):
	eliminated the $tag_size/$width mechanism.

	* (in all code base) replace "scalar @array" for "1+$#array",
	and "unless" for "if !" (still learning Perl).

2004-05-01  Stefano Bettelli  <bettelli@localhost>

	* Segment_dumpers.pl (dump_app13): this routine, together with
	dump_resource_data_block() and dump_IPTC_datasets(), can dump
	an APP13 segment (read, IPTC data, in particular).

	* Segment_parsers.pl (parse_resource_data_block): corrected
	a bug (the padding byte is not part of the resource block name).

	* Segment_parsers.pl (parse_unknown): non-printing characters
	are translated also here. Now, the output of get_description()
	for a Record object should not fool 'grep' into thinking that
	the output is binary.
	* Record.pm (get_description): this method now reworks ASCII
	strings a bit before displaying them. In particular it trims
	unreasonably long strings and replaces non-printing characters
	[\000-\037\177-\377] with their octal representation. Note,
	however, that "more chars" counts each non-printing char as four.

	* Segment_parsers.pl (parse_resource_data_block): non-IPTC
	records are now written in the root directory of an APP13
	segment, instead of the subdirectory "PHOTOSHOP_TAGS". This
	preserves the relative order with respect to the IPTC block.
	The parse_Photoshop_additional() method was removed. If
	there is a non-trivial record description, it is stored in
	the new "extra" field of the appropriate Record object.

	* Segment.pm (search_record): introduced "reserved" keys in
	the record search routine: if $key is exactly "FIRST_RECORD"
	/ "LAST_RECORD", the first/last record in the appropriate record
	list is returned.

	* Record.pm (new): Added a new field, "extra", which can be
	used to store additional information one does not know where
	to put. The need originated from APP13 record descriptions.
	Record::get_description() was modified to show the field.
2004-04-30  Stefano Bettelli  <bettelli@localhost>

	* Tables.pm (enum): removed all "custom" numeric-to-textual
	translations in %JPEG_RECORD_NAME. In fact, given that 
	Record objects now accept a non-numeric tag, these names
	can be written directly into the code.

	* Segment.pm (search_record): this new method is modelled on
	search_value_by_key (which can now be safely removed), but it
	returns a reference to the first occurrence of a record with
	a given key (this is handy for dumper routines).

	* Record.pm (set_value): this new method allows the modification
	routines not to deal with Record objects internals.

	* Record.pm (get): this new method is the "inverse" of the
	constructor (but it does not erase the record content). In 
	list context, it returns the following list: ($key, $type, $count,
	$dataref). In scalar context it returns $$dataref (note the
	dereferentiation). This is tricky (but handy).

2004-04-27  Stefano Bettelli  <bettelli@localhost>

	* Record.pm (extract): reorganisation + comments. extract() is
	renamed as decode(), and the inverse function is provided 
	under the name of encode(). Massive use of map. Danger!

2004-04-26  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.0.4

	* Record.pm (get_description): the ASCII description of a
	record does not require an entry in the hash tables provided
	by Tables.pm. If such an entry does not exist, a default label
	is provided. This allows me to drop a lot of undocumented or
	illegal entries in the aforementioned tables. What to do with
	this kind of records is still to be decided.

	* Record.pm: the length of an anonymous array reference is
	now calculated (it was fixed to 16), because I suspect it can
	change in other versions of Perl, as reported by Martin.

2004-04-25  Stefano Bettelli  <bettelli@localhost>

	* Segment_parsers.pl (parse_app3): double count for garbage
	bytes corrected in the last garbage test.

	* Segment_parsers.pl: all references to $this->{parsed}
	removed. In fact, if a segment remains with $this->{error}
	undefined, it is to be considered correctly parsed.
	Also, all informative messages which are not at error level
	are now treated with "warn", not "print".

	* Segment.pm (Directory_Banner): now a simple subroutine.

	* Segment.pm (get_description): Segment_Banner suppressed and
	its functionality inserted directly in this method, which can
	now show also any error condition occurred during the segment
	construction in the parsing stage (now all segments are shown).
	* Segment.pm (update): consistently with the previously stated
	policy, a segment with errors ($this->{error} not undefined)
	cannot be updated (so, it must be rewritten to disk as it is).

	* Segment.pm (new): new error handling strategy also for JPEG
	segments and underlying classes. The parsing routines in the
	constructor of a segment are now executed in an eval block;
	if any error occurs (in the Segment or Record class, which in
	turn implies that parsing was interrupted at some point and is
	therefore incomplete) the "error" member of the relevant segment
	object is set to a meaningful error message. If no error occurs,
	the same variable is left undefined. The reference to the segment
	object is returned in any case. In this way, a "faulty" segment
	cannot inhibit the creation of a Structure object; faulty segments
	should in no case be edited/modified, basically because their
	structure could not be fully understood. They can anyway be
	rewritten to disk untouched, so that a file with corrupted or
	non-standard segments can be partially edited without fear of
	destroying it. $this->{parsed} was suppressed.

	* Structure.pm (new): new error handling strategy. If there is
	an irrecoverable error in the constructor of a Structure object,
	the ctor returns undef and an error message can be retrieved
	with Image::MetaInfo::JPEG::Structure::Error(). This works
	by executing the parsing subroutines in the ctor in an eval
	block, and then checking the value of $@. In this way the
	creation of an Image::MetaInfo::JPEG::Structure object is
	similar to the creation of an Image::IPTCInfo object.

2004-04-22  Stefano Bettelli  <bettelli@localhost>

	* Segment_parsers.pl (parse_app1_exif): contrary to my belief,
	there exist IFD0 sections without a SubIFD pointer. Indeed, 
	the whole IFD0 section can contain no fields at all. I modified
	the code so that it does not abort if the link is not present.

	* Segment_parsers.pl (parse_app1_exif): some pictures declare
	they have a thumbnail, but there is no thumbnail link for it
	in the following of the 1st IFD. This case is now treated
	gracefully, without trying to access the undefined link.

2004-04-19  Stefano Bettelli  <bettelli@localhost>

	* Structure_comments.pm: this new file contains those functions
	which deal with comment segments in the files. It is loaded by
	Structure.pm, and contains the following functions:
	Structure::set_comment($index, $string),
	Structure::join_comments($separation, @selection).
	* Structure.pm (get_segment_indexes): this new method returns
	a list of indexes pointing to segments matching a given condition.

	* Structure.pm (show): this method (and its supporting methods
	in the lower level classes) were renamed as get_description().
	They now return a string instead of printing to standard output.

2004-04-18  Stefano Bettelli  <bettelli@localhost>

	* Tables.pm (enum): Introduced three unknown tags (231, 232, 240)
	in the HASH_IPTC_RECORD_2 hash (found in a "Canon EOS-1D" image).
	The treatement of these unknown/non-standard tags should be unified.

2004-03-17  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.0.3

        * Added a basic copyright notice based on GPL 2.
	* Segment_dumpers.pl (dump_com): this file will contain routines
	which dump segment records into the segment internal data area.
	The simplest routine is for comment blocks.

	* package names changed to Image::MetaInfo::Jpeg::X, where
	X is /Structure|Segment|Record|Tables/; the "highest level"
	package is "Structure".

	* Segment.pm: all segment specific parsing routines are now in
	a separate file (Segment_parsers.pl), which is "required" in 
	the main package file (which was already ~ 100kB).

2004-03-17  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.0.2

	* Tables.pm: new variable ($VERSION) for package version

	* Segment.pm (get_segment_data): this routine dumps the content
	of a segment into a scalar (this includes the segment preamble,
	that is 0xff, the segment marker and the segment data word).
	The data area is read from $this->{data}, not from the parsed
	records (one should provide other routines for storing, segment
	per segment, the [possibly modified] records into $this->{data}).

	* Segment.pm (parse_app1_xmp): this routine contains the simplest
	XML parses able to parse Adobe XMP packets (at least I hope). The
	layout of parsed records is a bit complicated, but this is the way
	XML works (I should be able to reconstruct the full XMP packet
	from this layout, comment excluded, at least I think).

2004-03-15  Stefano Bettelli  <bettelli@localhost>

	* Tables.pm (enum): deleted the GPS prefix from GPS tag names.
	Added all TIFF 6.0 tags which are not Exif 2.2 tags to the
	%HASH_APP1_IFD hash, and also looked at tiff.h of libtiff for
	some other vendor specific tags.
	* Segment.pm (parse_app3): simplified, with the same trick
	as for parse_app1_exif (i.e., the update_offset_and_garbage
	local subroutine). This can be done better ...
	* Segment.pm (parse_app12): the routine parsing an APP12 segment
	is now more refined and readable; however, I don't have any
	documentation about this format, and only one example so far, so
	parse_app12 should be considered highly experimental.

2004-03-14  Stefano Bettelli  <bettelli@localhost>

	* Segment.pm (new): Deleted the "dirs" member in a JPEG::Segment
	object. There is now a new way to store properties in a segment.
	$segment->{records} gives access to a list of JPEG::Records; most
	of them contains segment properties (key-value pairs), but some
	are REFERENCE records: for these records, the key is a string
	carrying the name of a sub-directory, and the value is a reference
	to this sub-directory, whose structure is the same as for
	$segment->{records}. This mechanism replaces the $this->{dirs}
	hash, and is more flexible. Have a look at JPEG::Segment::show()
	for more details on how to inspect this structure. For instance,
	in APP1 and APP3 there are the following trees:

	               /--APP1--\             APP3
		      /          \             |
	         /--IFD0--\     IFD1       /--IFD0--\
		/          \              /          \
	     SubIFD        GPS         Borders     Special

	* Record.pm (show): change the test for numeric/non-numeric
	tags from $descriptor =~ /\d/ to $descriptor =~ /^\d*$/.

2004-03-13  Stefano Bettelli  <bettelli@localhost>

	* Segment.pm (store_record): a list reference can now be prepended
	to the argument list; in this case it is used instead of
	$this->{records}. This means that store_record can now be
	used instead of an explicit push also for "subdirectories"
	(provide_subdirectory): this new method searches (creates if
	absent) a REFERENCE record (an internal record linking to a
	subdirectory) and returns its value (the actual reference).
	The record can be inserted in any record list, and defaults
	to the main record list $this->{records}.
	(search_value_by_key): this now works as provide_subdirectory,
	i.e., the second argument is an optional record list reference.

	* Record.pm (show): change the prototype; now the second
	argument is a reference to a list of names, to be used as
	successive keys in the JPEG_RECORD_NAME hash to find the
	description of a numeric key. No argument is needed if the
	key is non-numeric. This allows for more flexibility and
	deeper structures. Other small cosmetic changes.

	* Segment.pm (show): change the test from (defined $this->{parsed})
	into ($this->{parsed} eq "ok") [this was a bug]
	(show_directory): this new method prints all records in a given
	record directory. It is called initially by show(), and can call
	itself when it finds a record containing a reference to another
	record list (this supersedes the old sub-directory mechanism).

	* Segment.pm (search_value_by_key): changed order of arguments.
	Now $dir is the second argument; if it is defined it looks in
	$this->{dirs}{$dir}, otherwise it looks in $this->{records}

	* Record.pm (new): added a "reference" type for records. This
	type will be used only internally to link to subdirectories.
	The show() method and the Tables..pm file needed to be updated.
2004-03-12  Stefano Bettelli  <bettelli@localhost>

        * Save current state as version 0.0.1
	* Segment.pm (parse_app1_exif): sometimes, we have broken pictures
	with a thumbnail in APP1 with an actual size which is shorter than
	the predicted size; nonetheless, the thumbnail is often valid, so
	this case deserves only a warning if the difference is not too
	large (currently, 1 byte).

2004-03-06  Stefano Bettelli  <bettelli@localhost>

	* Segment.pm (create_record, read_record, store_record):
	The data reading routines have been revolutionised in order to
	be simpler, less, and more uniform. Their prototypes:
	create_record(tag, type, dataref/offset, count)
	             [returns a record reference]
	read_record  (     type, dataref/offset, count)
	             [returns reference->get_value()]
	store_record (tag, type, dataref/offset, count)
	             [inserts + returns record reference]
	(get_last_record_value), as a consequence could be dropped and
	many other methods needed to be updated to reflect the new 
	prototypes. In particular, all direct calls to the JPEG::Record
	constructor have been replaced by create_record.
	* Record.pm (new): The arguments of a record constructor 
	are now: (key, type, dataref, count, endiannes). Other internal
	methods have been updated accordingly (extract).

	* Segment.pm (data): access to a substring of $this->{data}
	is now mediated by this method.

2004-03-05  Stefano Bettelli  <bettelli@localhost>
	* Deleted all "Aborting ...\n" in 'die' statements, because
	it is obvious and because showing the index of the error
	causing line is better (and code is shorter ...)
	* Segment.pm (new): added a private transient member which
	stores the "current" endianness value; this is only meaningful
	during the parsing routines, and it is reset to undef at the
	end of the constructor. This change gets rid of a very tedious
	parameter to be passed all around.

	* Record.pm (get_size): the logic for calculating the memory
	footprint of a record is now in this class static method.
	Moreover, some details have been abstracted in local variables
	and @JPEG_RECORD_TYPE_LENGTH is now private in the record class.
	Some copies dropped in favour of using references.
2004-03-01  Stefano Bettelli  <bettelli@localhost>

	* Segment.pm (search_value_by_key): return as soon as a matching
	key is found (identical keys are an error anyway!)
	* Segment.pm (get_last_record_value,add_record,search_value_by_key)
	use references instead of copying arrays (at least, I hope this
	is the effect of using @$refname instead of @{$refname}.

2004-02-27  Stefano Bettelli  <bettelli@localhost>

	* replaced computed gotos in Record.pm with ifs for portability.
	More robust parsing of IPTC/NAA data. Added parsing of APP3 and
	APP14. Preliminary work on APP12 and XML meta-data in APP1.

2004-02-04  Stefano Bettelli  <bettelli@localhost>

	* Initial code, with splitting of JPEG sections and parsing of
	COM, APP0, APP1, APP13 (just a try), DQT, DHT, SOF_n and SOS. Only
	showing the parsed tags is supported. Files: Record.pm, Section.pm,
	Structure.pm, Tables.pm

Revision history for Perl extension Image::MetaInfo::JPEG.

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