Perceptual Image Diff


PerceptualDiff is an image comparison utility that makes use of a computational model of the human visual system to compare two images.

This software is released under the GNU General Public License.


Why? I can look at the images myself

So why would I use a program to tell me if two images are similar if I can tell the difference myself by eyeballing it?

Well the utility of this program really shines in the context of QA of rendering algorithms.

During regression testing of a renderer, hundreds of images are generated from an older version of the renderer and are compared

with a newer version of the renderer. This program drastically reduces the number of false positives (failures that are not actually failures)

caused by differences in random number generation, OS or machine architecture differences. Also, you do not

want a human looking at hundreds of images when you can get the computer to do it for you nightly on a cron job.


The relevant theory behind the image metric can be found in the following resources:

Download Source or Precompiled binaries

The source code and OSX, Windows binaries are available for download. Note: earlier builds were named pdiff but due to naming conflict newer builds are named ‘PerceptualDiff’

Build Instructions

This project makes use of the Cross Platform Make Utility , and the FreeImage library. You will also need Subversion to obtain the source.

1. Obtain the source from sourceforge: svn co pdiff
2. Edit CMakeLists.txt as necessary to point to libtiff
3. Type cmake .
4. Type make .
5. PerceptualDiff should be compiled for your target system


PerceptualDiff image1.tif image2.tif [options]

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