06-09-2011, 08:57 AM
If you want the smallest file possible, try PNGGauntlet. I personally use PNGOut from the command line, but PNGGauntlet is easier to use. Most conversion utilities and graphic editors save the file with a quicker compression routine so that it will save faster. PNGGauntlet will take longer, but the resulting file size is smaller than what a typical program would output.