comparing GIF images pixels

Question

I need to compare 2 same-size, nearly identical images for exact differences in the RGBs of every pixel.

I would like to find a tool that already does it... seems nowhere to be found on google, strangely.

If I could even find a tool to print out the RGB values of every pixel I could compute it by hand (the images are small enough) or load that input for my tool. Again, couldn't find anything.

Otherwise I look for a simple C library to decode GIFs and access each pixel... recommendations? I see quite a few on google, most look old and have no documentation.

I hope someone with more exposure to image processing can help me solve this this somewhat trivial task in one way or another without spending too many hours!!

Answer 1

Beyond Compare will do image comparisons and highlights differences.

http://www.scootersoftware.com/

Answer 2

What about SDL + SDL_Image (main site)?

You can easily open GIFs and load them on SDL_Surfaces to retrieve the pixel information you need..

Answer 3

If you have ImageMagick installed, it already does it.

Answer 4

If you're not opposed to Python, one option would be to use the Python Imaging Library (PIL), which provides Python bindings for native decoders for many file formats, including PNG and GIF.

This past summer, I wrote a few small apps to do RGB-wise comparisons of PNG images, in C++, pure Python, and Python using PIL. It would be trivial to make the PIL code work with GIF images.

If you want to roll your own, the "standard" C library for simple image manipulation is GD.