Re: [Gimp-developer] the Gimp lcms.c plug-in

[Øyvind Kolås <pippin gimp org>]

On Mon, Aug 27, 2012 at 4:08 PM, Elle Stone <l elle stone gmail com> wrote:
> My lcms2 plug-in now does do correct ICC profile conversions, from any
> RGB color space, to any RGB color space, at 8-bit integer, 16-bit
> integer, and 32-bit floating point.
>
> However, to get it to work, I had to modify the babl/babl/util.h file.

This is great news, since it means that the code works as intenended
but probably with slightly different intentions.

> After modifying the babl/babl/util.h file, 16-bit tiffs open
> correctly. As you might recall, with the default util.h file, 16-bit
> tiffs open with a mysterious and erroneous "gamma=2.2 correction"
> having been applied. This tiff issue has nothing to do with the lcms
> plug-in.

Data stored for higher bitdepths per pixel than 8 are assumed to be
stored with a linear gamma ramp, a higher level code where you
probably could do a similar tweak without changing core babl behavior
could be in ... digging through GIMP code ...
gimp/app/gegl/gimp-babl.c which contains code determining the data
expected to be managed, for all arbitrary profile source imagery it
would be recommended to store layer data in floating point.

/Øyvind K.
-- 
«The future is already here. It's just not very evenly distributed»
                                                 -- William Gibson