On Tue, Mar 8, 2011 at 3:12 PM, Bogdan Szczurek <thebod...@gmail.com> wrote:
>> Considering the use cases where fine grained control over the
>> resulting offset plates/actual ink used for C,M,Y,K to be a subset of
>> the more general cases where individual ink control is desired
>> (spot-colors (including metallic, glossy and other overprints) as well
>> as duo tone and more).
> I also have high hopes for GEGL, but I'd rather have it use some more
> abstract color model for that. I know it's not so simple—maybe even
> undoable–that way, but I do like the idea of color model that has
> complete coverage of visible spectrum.

Using a color model with full coverage of the visual spectrum would be
an extension along the lines of RGB and the responses of the human
visual system/physics, entirely additive. Spectral processing is not
similar to subtractive models like CMYK  models needed for simulating
print, mixing aspects, subsurface scattering, ink interactions and
more (some of which are better indirectly modeled by ICC transforms
backed by actual test-runs).

>> with almost enforced
>> strict working spaces for the algorithms to ensure predictability. The
>> ability to do separation to CMYK, spot colors and more with associated
>> processing on such will most easily be done as abstractions
>> implemented using a planar approach where each ink is represented by a
>> graylevel buffer.
> True enough, but we mustn't forget about target material
> characteristics when considering print (and soft proofing), paint
> printing order and their attributes (opacity among them too).

All of these, like the simulation of glossiness or reflectiveness of
metallic inks are things for the final separation/composite/simulation
though - which very well can take into account both substrate and
perhaps even an animated illuminant ;) Such soft-proofing would not be
a space that GEGL itself would be doing processing in however, even
though it might have op(s) to take the individual grey level buffers
to create an RGB simulation to be shown on a display,. taking into
account the RGB profile.

Allowing the user to configure a largeish set of predefinable inks for
separation and simulation/softproofing would possibly allow some very
nice workflows in GIMP and other softwares using GEGL.

Implementing the capabilities of doing such workflows is something
that only can happen after GIMP itself has more naive initial support
for storing its image data in GeglBuffers of higher bit depths. So if
someone wants to play with, research and make prototypes for such a
thing it would be a nice and welcome addition.

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