/ 
Image-Leptonica-0.04
River stage zero No dependents
/ Image::Leptonica::Func::ccthin

NAME

Image::Leptonica::Func::ccthin

VERSION

version 0.04

ccthin.c


            

              
              
ccthin.c
   PIX    *pixThin()
   PIX    *pixThinGeneral()
   PIX    *pixThinExamples()

FUNCTIONS

pixThin

PIX * pixThin ( PIX *pixs, l_int32 type, l_int32 connectivity, l_int32 maxiters )


            

              
              
pixThin()
    Input:  pixs (1 bpp)
            type (L_THIN_FG, L_THIN_BG)
            connectivity (4 or 8)
            maxiters (max number of iters allowed; use 0 to iterate
                      until completion)
    Return: pixd, or null on error
Notes:
    (1) See "Connectivity-preserving morphological image transformations,"
        Dan S. Bloomberg, in SPIE Visual Communications and Image
        Processing, Conference 1606, pp. 320-334, November 1991,
        Boston, MA.   A web version is available at
            http://www.leptonica.com/papers/conn.pdf
    (2) We implement here two of the best iterative
        morphological thinning algorithms, for 4 c.c and 8 c.c.
        Each iteration uses a mixture of parallel operations
        (using several different 3x3 Sels) and serial operations.
        Specifically, each thinning iteration consists of
        four sequential thinnings from each of four directions.
        Each of these thinnings is a parallel composite
        operation, where the union of a set of HMTs are set
        subtracted from the input.  For 4-cc thinning, we
        use 3 HMTs in parallel, and for 8-cc thinning we use 4 HMTs.
    (3) A "good" thinning algorithm is one that generates a skeleton
        that is near the medial axis and has neither pruned
        real branches nor left extra dendritic branches.
    (4) To thin the foreground, which is the usual situation,
        use type == L_THIN_FG.  Thickening the foreground is equivalent
        to thinning the background (type == L_THIN_BG), where the
        opposite connectivity gets preserved.  For example, to thicken
        the fg using 4-connectivity, we thin the bg using Sels that
        preserve 8-connectivity.

pixThinExamples

PIX * pixThinExamples ( PIX *pixs, l_int32 type, l_int32 index, l_int32 maxiters, const char *selfile )


            

              
              
pixThinExamples()
    Input:  pixs (1 bpp)
            type (L_THIN_FG, L_THIN_BG)
            index (into specific examples; valid 1-9; see notes)
            maxiters (max number of iters allowed; use 0 to iterate
                      until completion)
            selfile (<optional> filename for output sel display)
    Return: pixd, or null on error
Notes:
    (1) See notes in pixThin().  The examples are taken from
        the paper referenced there.
    (2) Here we allow specific sets of HMTs to be used in
        parallel for thinning from each of four directions.
        One iteration consists of four such parallel thins.
    (3) The examples are indexed as follows:
        Thinning  (e.g., run to completion):
            index = 1     sel_4_1, sel_4_5, sel_4_6
            index = 2     sel_4_1, sel_4_7, sel_4_7_rot
            index = 3     sel_48_1, sel_48_1_rot, sel_48_2
            index = 4     sel_8_2, sel_8_3, sel_48_2
            index = 5     sel_8_1, sel_8_5, sel_8_6
            index = 6     sel_8_2, sel_8_3, sel_8_8, sel_8_9
            index = 7     sel_8_5, sel_8_6, sel_8_7, sel_8_7_rot
        Thickening:
            index = 8     sel_4_2, sel_4_3 (e.g,, do just a few iterations)
            index = 9     sel_8_4 (e.g., do just a few iterations)

pixThinGeneral

PIX * pixThinGeneral ( PIX *pixs, l_int32 type, SELA *sela, l_int32 maxiters )


            

              
              
pixThinGeneral()
    Input:  pixs (1 bpp)
            type (L_THIN_FG, L_THIN_BG)
            sela (of Sels for parallel composite HMTs)
            maxiters (max number of iters allowed; use 0 to iterate
                      until completion)
    Return: pixd, or null on error
Notes:
    (1) See notes in pixThin().  That function chooses among
        the best of the Sels for thinning.
    (2) This is a general function that takes a Sela of HMTs
        that are used in parallel for thinning from each
        of four directions.  One iteration consists of four
        such parallel thins.

AUTHOR

Zakariyya Mughal <zmughal@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2014 by Zakariyya Mughal.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.