Performance problem with colorspace conversion in lcms2
lukast.dev at gmail.com
Tue Oct 1 20:15:30 UTC 2013
I'm working on Gmic as you know and I hit performance bottleneck
when converting Krita layers to gmic layers and back and making the whole
experience for Krita artists quite slow.
What I'm doing -- converting Krita colorspace uchar 8-bit rgba to float
I found out that the bottleneck is actually in lcms2
There is benchmark where is roundtrip conversion rgb8-float-rgb8
You can run it at
>From the valgrind log  we can see that the bottleneck (98% of time) is in
and there in
and there it looks like it is using a lot of math pow, exp per pixel which
is of course slow.
For 3840x2400 image it takes 6,5 second to convert from rgba8 to rgba32
float on my laptop.
I wrote this hack to convert Krita pixels from rgba8->rgba32 float:
It takes 120 ms to convert Krita layer to gmic with this hack way, so it's
Of course it ignores all rendering intends and profile, but I wonder if
there is some way to tell
lcms2 to do it stupidly and simply and avoid stuff like: pow, exp1 per
pixel and cmsEvalToneCurveFloat?
 valgrind log
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