Comment 1 for bug 172138

Originator: NO

Well... there is a problem with that threads clumping things into png8 and
png32. The PNG spec actually allows for five different types, with
"indexed" being one, and the type supporting "png32" ranges from "PNG4" bit
to "PNG64" bit.

Going to indexed PNG (what that thread calls PNG8) takes color reduction,
dithering, and other lossy and subjective changes (consider the complexity
in my first bit of info there). A dedicated bitmap tool like GIMP or
ImageMagick does better to do such.