Re: [Gimp-developer] c2g improvements

[Jacek Poplawski <jacekpoplawski gmail com>]

On Sun, Jun 3, 2012 at 10:40 PM, Jon Nordby <jononor gmail com> wrote:

c2g is a GEGL operation. You will find it in operations/common/c2g.c
in the GEGL tree.

I know this code pretty well because I was analizing it for days and implementing my own version for delaboratory :)

I would recommend first finding out what causes the current slowness
you experience: Is it the GEGL integration in GIMP? (compare c2g usage
in GIMP with using GEGL directly). Is it due to some overhead in GEGL
core? Or maybe there is room for optimization in the operation itself?

there
 are few things... reading from 3 different arrays is 3 times slower 
than reading from 1 array, at least under Linux... but the overall 
algorithm does too much things that's why I proposed to create "c2g 
lite" which will not be so mathematically correct but give similar 
effect... for instance is relative brightness really so important in 
envelopes.h? also the luts are generated everytime from start, while I 
found out that generating one big array and use subset of data give 
similar results