[Gegl-developer] Color temperature correction GeglOperation

[Jan Heller]

Hi,

On 11:09, Sat 26 Apr 08, Øyvind Kolås wrote:
> On Fri, Apr 25, 2008 at 6:52 PM, Jan Heller <jan.heller at matfyz.cz> wrote:
> 
> > I wrote it to better familiarize myself with
> > Gegl and I am posting it here in hope it will be useful for
> > others.
> 
> I think it is a good operation to have, so I have commited a slightly
> modified version to svn.

Nice, thanks!

> 
> GEGL and babl deals with the out of gamut handling themselves at a
> later stage, during processing we preserve headroom and footroom. This
> allows us to change the contrast of the image to bring details back in
> later. The implemented gamut handling also seemed to introduce banding
> that  the conversions in babl does not.

Good to know.

> 
> It would also be nice to replace the planckian locus lookup table with
> a function that approximates it.

I played with MATLAB for a while and came up with rational
functions of degree 5 that approximate the Planckian locus
dataset reasonably well. Attached is a modified version of
the operation using these approximations.

Regards, 
 Jan
-------------- next part --------------
A non-text attachment was scrubbed...
Name: color-temperature.c
Type: text/x-csrc
Size: 5456 bytes
Desc: not available
Url : /lists/gegl-developer/attachments/20080426/d69d9e97/attachment.bin