S-Ultra PNG Compressor is a $14.95 Windows application for lossless compression of PNG files. The program’s interface won’t win any design awards. It’s all very basic: click an "Add" button to select your files, check a couple of boxes to set compression levels and click "Start" to kick the process off. Compression can be very slow, especially if you’ve chosen the maximum level 2 and level 3 options -- several seconds per file. Try it out with a small number of files, first. There are more issues. The demo only works with small images under 70KB, and it automatically overwrites… [Continue Reading]