Legacy ImageMagick Discussions Archive

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 ...

Thank you for your quick response.

At 6.8.6-5, this modified code has wrong calculation.
node_info->quantize_error+=count*sqrt((double) (error.red*error.red+
count*error.green*error.green+count*error.blue*error.blue+
count*error.opacity*error.opacity));

In sqrt all count multiplication must be ...

I found tree walking mistake for RiemersmaDither function.

* ImageMagick-6.8.6-4/magick/quantize.c

/*
Identify the deepest node containing the pixel's color.
*/
node_info=p->root;
for (index=MaxTreeDepth-1; (ssize_t) index > 0; index--)
{
id=ColorToNodeId(cube_info,&pixel,index);
if (node ...

quantize_error summarization has been changed at 6.4.1-3

* magick/quantize.c

- 6.4.1-2

node_info->quantize_error+=sqrt((double) (error.red*error.red+
error.green*error.green+error.blue*error.blue+error.opacity*
error.opacity));

- 6.4.1-3

if (IsColorSimilar(image,p,p+count ...