| One great resource for GIF-related explorations is Matthew Flickinger's "What's In A GIF" project: * https://www.matthewflickinger.com/lab/whatsinagif/index.html The original version is apparently from ~2005 and is used as the basis of the giflib docs referenced by the original article[0]. (The giflib docs do expand on the content of the original, so are still worth reading.) But Matthew Flickinger's original version has continued to be updated as recently as 2022[1] and now includes two helpful browser-based GIF tools: * GIF Explorer: https://www.matthewflickinger.com/lab/whatsinagif/gif_explor... * GIF Encoder: https://www.matthewflickinger.com/lab/whatsinagif/gif_encode... GIF Explorer displays the "interpreted" bytes of any GIF file in an almost "literate" style and has an UI/UX which I'd be really interested to see used in a generic reverse-engineering/binary viewer tool. GIF Encoder enables you to create an image in the browser & see how it is GIF encoded. I have a rant about how modern GIF usage could be so much better than it is (and still be within the original specification) but instead of subjecting you to that I'll subject you to this project of mine instead: https://audiogif.rancidbacon.com [0] https://giflib.sourceforge.net/whatsinagif/index.html [1] https://github.com/MrFlick/whats-in-a-gif |
The first time around, I struggled a lot with decoding errors. Many years later, after being a more experienced developer, I wrote the LZW decompression with unit tests. Doing so forced me to think about each edge case, and fix issues without breaking existing functionality. Very quickly, I was able to open pretty much any GIF file I threw at it!