[Gimp-developer] Possible approach for some non-sRGB GEGL/GIMP color workflows

[Øyvind Kolås <pippin gimp org>]

I've been thinking about how different color-space aware workflows
could work in our future GEGL powered GIMP. In particular about the
on-going theme of how to deal with "slight HDR" images, that have a
gamut including colors that are slightly outside the 0.0-1.0 range for
linear sRGB.

The primary goal will still be adapting channel displays; histograms
etc. to encompass/translate to show the <0.0 and >1.0 values; in
relation to a defined target/output profile. A hybrid linear-centric
approach might also work well.

If we on import linearise the data (using the RGB primaries of the
source color space), and then scale values down based on the magnitude
of the most intense primary, and pretend that the resulting data is
"RGBA float"; there will neither be cross component contamination nor
"out-of-ui-range" values.

I have not done actual experiments - to see the impact doing this
would have on the visual result, it gives up some aspect of color
management - but deal correctly with the tone-response curves. I
suspect the dominant side effect will be a slight loss in luminance.

/pippin