Here's a tool I wrote some time ago when I was trying to remove backgrounds and separate images into different parts. It is an image-comparison tool that takes two images of the same size and outputs the differences. You can control what it means for two images to be "same" using a tolerance threshold, where 0 tolerance means two pixels must be exactly the same, while higher tolerance means they can be somewhat different and still be considered the same. Tolerance is an important feature because if someone decided to use lossy formats (eg: JPG), a green pixel might just be slightly different from another green pixel, and you don't want to use an exact match for filtering purposes. Example Download http://www.himeworks.com/pixel-compare/ Usage is simple: drag and drop two images onto the tool, ctrl+Z to get the difference, then ctrl+C to copy to clipboard. Other There are probably many tools available out there that provide the same functionality, possibly with better heuristics and more flexible support. Imagemagick for example provides a variety of image comparison tools. However, it's command-line...and for my purposes it wasn't easy to use since I need to adjust the tolerance very often. If you know of any that are easy to use feel free to link them. Preferably with previews of how they look.