Re: MMX speedup for Floyd Steinberg error diffusion

On May 12, 9:06 am, "Novosad, Stephan R." <spamt...@xxxxxxxxxx>
wrote:
Terje wrote:
To do a mathematically perfect job I would start with a 5:5:5 (32 K) or
4:4:4 (4 K) table, with each entry being the start of a list of all the
possible palette entries for that entry:

Somewhat interesting as I initially quantize to 4,096 bins, and
then reduce the palette using a pairwise clustering algorithm.

This thread has made it clear that there are experienced graphics
people reading the group, so I hope it's okay to veer into an off-
topic tangent...

I have asked this question in comp.graphics and related newsgroups but
either gotten nowhere or received advice that didn't make sense: Does
anyone have any links to resources (or can describe the basic theory)
of dithering a picture using an ordered matrix (ie. bayer 4x4, etc.)
but fitting to an arbitrary palette? The only code examples I've seen
have been for ordered palettes with the same number of bits per
component (ie. 8 colors, 236 colors, etc). I have a need to dither
using an ordered matrix but fitting to an arbitrary palette.

Photoshop can do this, but it's the only program I've seen that can.
Someone referred me to ImageMagick, but that only offers ordered
dithering to ordered 2^n palettes, so looking at the source doesn't
help me...

.

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