Simple program that uses libpng to progressively read and write shrunken pngs
Used for learning about coroutines, PNGs, etc. and can be further developed.
How to use:
./pngshrink inFile outFile sampleRate
i.e.
./pngshrink palm-tree.png palm-tree-mini.png 3
Will create a smaller (1/3 size) valid png image file of a palm tree