Proposal: Quantize Bulk Reduce Acceleration

[yoya]

Hi, all.

I would like to propose QBRA (Quantize Bulk Reduce Acceleration) configuration to enable rapid color reduction.

The explanation of idea is here.
- http://d.hatena.ne.jp/yoya/20130724/im

With only a small code addition and without changing the fundamental algorithm we can get a performance boost.
However image quality deteriorates slightly, disabled by default is good.

Source code patch is here. (base on 6.8.7-0)
- QBRA substance patch
-- https://github.com/gree/YoyaMagick/comm ... dcd7620bb5
- QBRA configure patch (--enable-qbra, disabled by default)
-- https://github.com/gree/YoyaMagick/comm ... 2dcc66f30b

Thanks!

[magick]

Color reduction acceleration is an often requested enhancement. We'll add your patch to ImageMagick within a day or two. Thanks.