Decompress PNG using zlib

Question

How can I use zlib library to decompress a PNG file? I need to read a PNG file using a C under gcc compiler.

Answer 1

Why not use libpng? The PNG file format is fairly simple, but there are many different possible variations and encoding methods and it can be fairly tedious to ensure you cover all of the cases. Something like libpng handles all the conversion and stuff for you automatically.

Answer 2

I've code once a basic Java library for reading/writing PNG files: http://code.google.com/p/pngj/

It does not support palleted images but apart from that[Updated: it supports all PNG variants now] it's fairly complete, simple and the code has no external dependencies (i.e. it only uses the standard JSE API, which includes zip decompression). And the code is available. I guess you could port it to C with not much effort.