pngquant - 2.13.1-1 main

pngquant is a command-line conversion utility to quantize and dither truecolor
PNG images, especially those with a full alpha channel, down to 8-bit (or
smaller) RGBA-palette PNGs. Such images are usually two to four times smaller
than the full 32-bit versions, and partial transparency is preserved quite
nicely. This makes pngquant especially useful both for Web sites and for
PlayStation 2 development, where one of the texture formats is
RGBA-palette-based (though not PNG-compressed).
This is the same technique used for many of the images on the Miscellaneous
Transparent PNGs page (http://www.libpng.org/pub/png/pngs-img.html), and
the results are often indistinguishable from the original, truecolor PNG
images.
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Optimizers (like pngcrush and optipng) optimize the compression, usually
losslessly, while pngquant quantizes colors down to 256 (or fewer) distinct
RGBA combinations, which is lossy.