
@C1@c@b@_ Quantization

     To reduce the number of colors in an image.

@s@b Note
     It is not recommended to use quantization for the purpose of saving
     disk space because JPEG is better at that and retains more info than
     quantization as well.

     Several Quantization method exists

@b  Fast256
     An effective and relatively accurate quantization implementation.
     However, accuracy for reducing colors to other than 256 colors
     is unknown.
@b  median cut
     The most popular and accurate one. It takes more CPU time however.
     (in this pre-release, this method is not implemented.  General
     purpose quantization can still be achieved thru external bindings
     to djpeg or ppmquant. See sample bindings).
@b  Octree
     A simple and fast method which gives acceptable results for most
     images.
@b  Bugs
     Only Fast256 is implemented in this pre-release.

