On 12.08.2010 14:46, Rupert Weber wrote:
> On 08/12/2010 12:32 AM, James Cox wrote:
>> sRGB has only been around since 1996.  I suspect that the gimp version
>> dates from before that, or at least before sRGB came into common use.
> That would certainly explain it.
>> I don't think we want our color profiles to affect layer blending, so I
>> think it is best that we choose a single color space and stick with it.
> I was wondering about that. Right now, that's the behavior.
> But if you had two identical images differing only in color profile,
> should the same action (say, "increase contrast by 30%") deliver
>       (a) the same visual result (gamut permitting), or
>       (b) the same RGB values?
> Wouldn't (a) be preferable, even if it is different from current behavior?

I guess pretty much everyone agrees that ideally the color profiles of imported 
should neither affect layer blending nor any tool's characteristics.

The only sane way to achieve this is, like James says, to "choose a single 
color space
and stick with it". This is possible with floating point processing (GEGL).
All imported image data gets convert to, say scRGB, processing take places, and 
on export
data may be converted to a different color space, if necessary.

Changing the working color space is a stop-gap solution for 8-bit processing, 
to work around
excessive rounding losses, IMO. Now if you want to keep the operations' 
characteristics unchanged,
you would have to put the conversion code inside of _each and every_ one of the 
tool, filter and
blendmode routines.

So, i think GIMP should Get It Right for GEGL processing, while certain 
deviations of
operations' characteristics are tolerable for 8-bit processing.

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