libpng

Whose bright idea was it to write an image handling library with callbacks?
Why so many functions as options?
Why do you have to guess whether it's bits per pixel or bits per colour?
Why can I hear Hallelujah blasting from my neighbours' garden?

Ugh!

another thing that stinks about libpng: they came up with an animated format called MNG that only firefox bothered to implement support for. the format was deemed insanely complex. eventually, firefox scrapped it in favor of APNG... a simple animated format that added GIF like abilities to PNG. libpng refused to accept APNG thinking that their bloated MNG was superior.

if, however, they were to accept the APNG patches, every browser would eventually have support for APNG, and that would mean we could actually have an animated image format superior to GIF -- with better compression, more than 256 colors, alpha transparency, etc.