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+pdiff - 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.
+
+Build Instructions
+1. Download cross platform make from http://www.cmake.org
+2. Download libtiff from http://www.libtiff.org. Download libpng from http://www.libpng.org
+3. Edit CMakeLists.txt to tell it where to find your tiff library
+4. Type cmake .
+5. Type make . (or on Windows systems cmake makes a Visual Studio
+Project file)
+6. To specify the install directory, use make install DESTDIR="/home/me/mydist"
+
+Usage
+
+pdiff 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 oberserver 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 perceptably 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
+
+Credits
+
+Hector Yee, project administrator and originator - hectorgon.blogspot.com
+Scott Corley, for png file IO code
+Mick Weiss, Linux build and release & QA
+Carl Worth, Rewrite as library, depend on cairo, and port to C
+\ No newline at end of file