mageAlpha converts 24-bit PNG to paletted 8-bit with full alpha channel. This greately reduces file sizes with only minor loss of quality. Such images are compatible with all browsers, and even degrade well in IE6.
ImageAlpha can achieve conversion quality better than
Macromedia Fireworks by employing latest pngquant, pngnq.
Even images that need more than 256 colors can be made more compressible using special alpha-channel-aware posterizer.