Comparing images in pure Ruby (and how Github's image diff works)

Very enjoyable. Image manipulation/detection/recognition is a field that actually starts out pretty simple (I was surprised, I assumed it would be fiendishly math-heavy), but scales well into the dissertation-level.

The article is a pretty cool highlight of some low-hanging fruit. I'd like to see something using a n-neighbor-aware technique instead of pixel-by-pixel to detect shifting/scaling/rotation in a direction in addition to color change, but I'm sure those are much longer articles.

Just looking for the code? Here you go:

https://gist.github.com/923894 https://gist.github.com/925244 https://gist.github.com/924996