A program that compares two images using a perceptually based image metric

Copyright (C) 2006 Yangli Hector Yee

yeehector@users.sourceforge.net

http://pdiff.sourceforge.net

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details in the file gpl.txt.

1. Download cross platform make from http://www.cmake.org
2. Download freeimage from https://sourceforge.net/projects/freeimage (mac: brew install freeimage, ubuntu: apt-get install libfreeimage-dev)
3. Type cmake .
4. Type make .
5. To specify the install directory, use make install DESTDIR="/home/me/mydist"

Command line:

perceptualdiff image1.(tif | png) image2.(tif | png) [options]
-verbose : Turns on verbose mode
-fov deg : Field of view, deg, in degrees. Usually between 10.0 to 85.0.
           This controls how much of the screen the observer is seeing.
           Front row of a theatre has a field of view of around 25 degrees.
           Back row has a field of view of around 60 degrees.
-threshold p : Sets the number of pixels, p, to reject. For example if p is
               100, then the test fails if 100 or more pixels are
               perceptibly different.
-gamma g : The gamma to use to convert to RGB linear space. Default is 2.2
-luminance l : The luminance of the display the observer is seeing. Default
               is 100 candela per meter squared
-colorfactor : How much of color to use, 0.0 to 1.0, 0.0 = ignore color.
-downsample : How many powers of two to down sample the image.
-scale : Scale images to match each other's dimensions.
-sum-errors : Print a sum of the luminance and color differences.
-output foo.ppm : Saves the difference image to foo.ppm

Check that perceptualdiff is built with OpenMP support:

$ ./perceptualdiff | grep -i openmp
OpenMP status: enabled

• Hector Yee, project administrator and originator - hectorgon.blogspot.com
• Scott Corley, for png file IO code
• Tobias Sauerwein, for make install, package_source Cmake configuration
• Cairo Team for bugfixes
• Jim Tilander, Rewrote the IO to use FreeImage.

• 1.0 - Initial distribution
• 1.0.1 - Fixed off by one convolution error and libpng interface to 1.2.8
• 1.0.2 - [jt] Converted the loading and saving routines to use FreeImage
• 1.1 - Added colorfactor and downsample options. Also always output difference file if requested. Always print out differing pixels even if the test passes.
• 1.1.1 - Turn off color test in low lighting conditions.
• 1.1.2 - Add OpenMP parallel processing support and fix bugs.