NAME

Math::PSNR - Calculate PSNR (Peak Signal-to-Noise Ratio) and MSE (Mean Square Error).

VERSION

This document describes Math::PSNR version 0.02

SYNOPSIS

    use Math::PSNR;

    my $psnr = Math::PSNR->new(
        {
            bpp => 8,
            x   => [ 1.1, 2.2, 3.3, 4.4, 5.5 ],
            y   => [ 9.9, 8.8, 7.7, 6.6, 5.5 ],
        }
    );

    # Calculate MSE
    $psnr->mse;

    # Calculate PSNR
    $psnr->psnr;

    # Access to member variable of x
    $psnr->x(
        {
            r => [ 1.1, 2.2, 3.3, 4.4, 5.5 ],
            g => [ 1.1, 2.2, 3.3, 4.4, 5.5 ],
            b => [ 1.1, 2.2, 3.3, 4.4, 5.5 ],
        }
    );

    # Access to member variable of y
    $psnr->y(
        {
            r => [ 9.9, 8.8, 7.7, 6.6, 5.5 ],
            g => [ 9.9, 8.8, 7.7, 6.6, 5.5 ],
            b => [ 9.9, 8.8, 7.7, 6.6, 5.5 ],
        }
    );

    # Calculate MSE of three components signal (e.g. RGB image)
    $psnr->msr_rgb;

    # Calculate PSNR of three components signal (e.g. RGB image)
    $psnr->psnr_rgb;

DESCRIPTION

This module calculates PSNR (Peak Signal-to-Noise Ration) and MSE (Mean Square Error).

PSNR and MSE are the index of measuring quality between different signals. They are commonly used to evaluate quality of images.

This module can deal with single component signals (e.g. monochrome image) and three components signals (e.g. color (RGB) image).

More examples are in my GitHub repository. https://github.com/moznion/p5-Math--PSNR

INTERFACES

Math::PSNR->new( bpp => $bpp, x => $x, y => $y )

Creates an instance. Attributes are as follows:

bpp

Specify the bpp (bit per pixel). It sets 2^(bpp) - 1 to maximum power ("maximum power" means maximum allowable value of signal).

is : rw

This attribute is rewritable. Default accessor to this attribute is provided.

isa : Int

Please specify value of this attribute as integer.

default : 8

This attribute has default value. If bpp is not specified, it will be set 8 (bit).

required : 0

You do not have to set value of this attribute at constructor.

x

One side of signal for calculate PSNR and MSE.

is : rw

This attribute is rewritable. Default accessor to this attribute is provided.

isa : ArrayRef|HashRef

Please specify value of this attribute as numerical array reference or hash reference.

required : 1

You must set value of this attribute at constructor.

y

Another signal for calculate PSNR or MSE.

is : rw

This attribute is rewritable. Default accessor to this attribute is provided.

isa : ArrayRef|HashRef

Please specify value of this attribute as numerical array reference or hash reference.

required : 1

You must set value of this attribute at constructor.

METHODS

mse

This function calculates and returns MSE of single component signal. This function requires values of attribute x and y that is numerical array reference. Signal (array) length of x and y must be the same.

This function can use cache. If instance is immutable, this function returns previous calculated result.

psnr

This function calculates and returns PSNR of single component signal. This function requires values of attribute x and y that is numerical array reference. Signal (array) length of x and y must be the same.

This function can use cache. If instance is immutable, this function returns previous calculated result. And this function uses cache of MSE if it is available.

mse_rgb

This function calculates and returns MSE of three components (RGB) signal. This function requires values of attribute x and y that is hash reference. Those hash references must have three components (keys of hash are 'r', 'g', and 'b'). Signal length of each components (keys) of x and y must be the same.

This function can use cache like above-functions.

psnr_rgb

This function calculates and returns PSNR of three components signal. This function requires values of attribute x and y that is hash reference. Those hash references must have three components (keys of hash are 'r', 'g', and 'b'). Signal length of each components (keys) of x and y must be the same.

This function can use cache like above-functions.

CONFIGURATION AND ENVIRONMENT

Math::PSNR requires no configuration files or environment variables.

DEPENDENCIES

Mouse (version 1.02 or later)
Test::Exception (version 0.31 or later)
Test::Warn (version 0.24 or later)

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to bug-math-psnr@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

moznion <moznion@gmail.com>

LICENCE AND COPYRIGHT

Copyright (c) 2012, moznion <moznion@gmail.com>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.