Pngnq is a tool for quantizing PNG images in RGBA format.

Pngnq is an adaptation by Stuart Coyle of Greg Roelf's pnqquant using
Anthony Dekker's neuquant algorithm.

The neuquant algorithm uses a neural network to optimise the color map
selection. This is fast and quite accurate, giving good results on many
types of images.

WWW: http://pngnq.sourceforge.net/