Re: MMX speedup for Floyd Steinberg error diffusion

rep_movsd <spamtrap@xxxxxxxxxx> writes:
On May 10, 10:48 pm, Phil Carmody <thefatphil_demun...@xxxxxxxxxxx>
wrote:

You might be able to just do some kind of octree algorithm.
You could even hard-code the partitions.

(Octree's also possible in 256-colours too, of course. You can
even create a slightly optimised palate by using 2 passes and
crudely bin-counting on the 3 axes.)


I implemented 4 different quantizers, Octree, Median cut, Wu and
NeQuant ( the last 2 adapted from the FreeImage library ) and it seems
that Wu quantization gives the best results, followed by octrees, The
other 2 never quite get as good results as far as I could see.

What do you mean by "bin-counting on the 3 axes" ?

Bin counting is just building a histogram. So pretend
there's complete independence on the 3 axes, and
populate 3 histograms with tallies. Decide how to split
on each axis based purely on its own histogram.
This works quite poorly if there's a very high correlation
between the three axes. Mapping to some kind of
luma-chroma space first can help fix that.

Phil
--
Dear aunt, let's set so double the killer delete select all.
-- Microsoft voice recognition live demonstration

.

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