Best PNG Compression Software?
PngOptimizer 165KB in about 2 seconds.
Image quality is untouched.
I've only ever used pngcrush but it works well and has plenty of options.
Just for a quick benchmark, I downloaded 170 random PNGs from different websites on the internet, totaling about 8MB. Here are the results:
Original: 8,403,619 bytes total
PNGCrush: 7,398,194 bytes total
Optipng: 7,340,167 bytes total
PNGOUT: 6,938,205 bytes total
So it seems PNGOUT (or any GUI based on it) is the best choice if size is your primary goal. These are all lossless transformations.