> On 12 August 2010 00:17, Edward Coffey <edward.cof...@gmail.com> wrote:
>> My understanding of GEGL (and, I assume, a fully GEGL-based GIMP) is
>> that colors will be represented internally as linear-light RGB(A)
>> structures. Given that (and please correct me if I'm already veering
>> off track), how are the red, green and blue illuminants defined? Are
>> they "virtual colors" that lie far enough outside the visible gamut
>> that they can completely contain it? Or are they something else, like
>> standard sRGB illuminants, or illuminants related to the color-space
>> defined for the image being edited?
> As yahvuu says, they are the sRGB primaries.
> You don't need to worry that the sRGB gamut is rather small since,
> because GEGL is using float, it can represent values outside the gamut
> as less than 0 or greater than 1.

That sounds good in theory, but there will be some very sharp edges in
practice.  What does the UI for the curve tool look like when possible
values are -FLOATMAX to +FLOATMAX.  What does the contrast tool do with
values above 1.0.  When I blend some layers with multiply mode they can
only get darker right?

I open up an image to make a small change to one corner. Why did other
parts of my image change color slightly?  Because Round tripping through a
color profile is not lossless (some profiles are worse than others).

I have a picture of some flowers that I want to make as red as possible to
print on my AdobeRGB1998 printer - Instead of adjusting to 1.0, 0, 0 I
have to go to 1.1, -.03, -.07?  Or are you converting it to my destination
space and back again every time i make an edit?

You can hide the numbers entirely from the beginners.
The experts can get used to anything.
But the intermediate/enthusiasts are going to have a very hard time.

Adobe lightroom does something very similar, except it uses the ProPhoto
RGB primaries.  Lightroom can get away with this because it's usage is
very different.  It always receives image data with a nebulous a color
space (data from the camera's sensor) and will always export the data to
different color space.  And people still complain about the internal color

Jay Cox

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