Re: [Gimp-developer] Interest for CMYK support

[Octavio Paez Osuna <opaezosu gmail com>]

I am interested. I am new ti GIMP development, which I do in my spare time.
I am starting to modify the newsprint CMYK mode to directly separate into
CMYK layers instead of a flat image as it is now. The CMYK decompose
function appears to be broken in my version of 2.10, four black layers
appear. I will look into that also.

Cheers, and let me know what I can help with.

Octavio

On Sat, May 18, 2019 at 9:28 PM Øyvind Kolås <pippin gimp org> wrote:

> On Sat, May 18, 2019 at 10:33 PM Eleftheria Chatziargyriou via
> gimp-developer-list <gimp-developer-list gnome org> wrote:
> > Hello everyone,
> >
> > I am occasionally developing a colour theory library as a pet project and
> > oftentimes compare it against widely established tools. I was quite
> > surprised to see that GIMP doesn't offer any support for the CMYK mode.
> >
> > I did a bit of searching around and it seems that the feature was popular
> > enough to warrant a plug-in (Separate+) which now seems deprecated.
> Beyond
> > that, I also found a few scattered threads requesting this feature most
> of
> > which where redirected to the aforementioned plug-in.
> >
> > Is there any interest for seeing CMYK support as a part of gimp, or is it
> > beyond the scope of the project?
>
> It is very much in scope, and some of the internals are already ready.
> The underlying core GIMP imaging libraries babl and GEGL provide
> GIMP-2.10 with high-bit depth support. GEGL supports full internal
> color management and mixing of image buffers in grayscale, RGB, CMYK,
> CIE Lab color spaces of various bit depths and other aspects of pixel
> format encoding. For tasks as image loading/saving from JPG/TIFF,
> scaling, rotating, cropping, blurring, text-rendering, basic
> compositing and more GEGL already handles CMYK.
>
> Work is underway in GIMP's master branch completing refactorings that
> add the previous big feature improvement of babl. The extension of the
> pixelformat from keeping track of different encodings of possibly
> unbounded sRGB based pixel formats to include color space information
> as contained in RGB Matrix ICC profiles. That work which among GIMP
> developers is known as the space invasion, since it adds better
> support for color-spaces and it adds a space argument to many
> functions also lays the foundation for later starting to add support
> in GIMP for CMYK as a mode on par with RGB, Grayscale and Indexed.
>
> Even after that is in place, for *photos* I would strongly urge to
> work in RGB and use modern workflows with late-binding, totally
> avoiding the new CMYK mode, there is other graphic design use-cases -
> with vectors, text and more where it will be more useful; but not for
> basic things like retouching and color and light adjustment in
> photograhps. When constraints of other tools or workflow demands CMYK
> TIFF or JPGs, conversion should happen at export time similar to what
> separate+ provides, and the CMYK support would be limited to soft
> proofing with the CMYK gamut.
>
> /pippin - https://pippin.gimp.org/
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