[Magick-bugs] A bug in writing one-channel PNG-files from Magick++ ???

[valhalla at imagemagick.org]

> counts the existing colors first and simply puts them into the
> colormap when it finds that there are few enought colors. 

Forgot, this does work in 8-bit QuantumDepth but for 16-bit depth the
colors are lopped to 8-bit when traversing the tree.  A 16-bit depth tree
would consume far too much memory and be way too slow.  In the mean-time
you can count the exact number of colors with GetNumberColors() but if you
call QuantizeImage() it will treat close colors as the same in 16-bit
QuantumDepth.