Photoshop CS6
256-color image shows banding caused by low quality remapping (looks like only 15 bits of precision).
Images were created with pngquant 2.0.1 at default settings and Photoshop 13.0 with Save for Web and Perceptual palette. Optimized file sizes are from ImageOptim 1.4.5.
pngquant plug-in for Photoshop is now available.
256-color image shows banding caused by low quality remapping (looks like only 15 bits of precision).
More adavnced palette selection and correct remapping can avoid a lot of banding.
210KB (189KB optimized). Poor palette creates more dithering, which makes compression less efficient.
195K (117KB optimized). Better quantization and adaptive dithering give smoother image and almost 40% smaller file size after optimization.
Lack of support for palette transparency forces authors to use 195KB PNG24 (3.3 times larger file than PNG8+alpha).
Supports alpha channel in palette mode, and still gives less banding despite needing more palette entries for semitransparent shadow and anti-aliasing.
77KB (69KB optimized). Transparency dither still applies matte color, creating completely invalid result. Image has grainy look and jagged edges.
64KB (58KB optimized). Smallest file size and high-fidelity transparency.