libpng-1.2.30beta03 is available from
The changes are mostly cosmetic, merging changes from libpng-1.4.0beta19
into libpng-1.2.30beta03. There is an optimization of reading, where
the reading of
chunk length and chunk name are merged into a single 8-byte read, and
similarly with writing of the chunk length and chunk name. I doubt that
the speedup, while probably real, is perceptible.