On 12.08.2010 16:16, Graeme Gill wrote:
> yahvuu wrote:
>> I guess pretty much everyone agrees that ideally the color profiles of 
>> imported images
>> should neither affect layer blending nor any tool's characteristics.
>
> The whole point of color profiles is to describe how to interpret the
> device values as visual colors. So a tool that purports to work in a device
> independent colorspace, will (apart from gamut limits) have an effect that
> is not visually affected by the color profiles, but will of course have quite
> different affects on the device dependent values.

yes, on purpose. If i had to put it to a motto, i'd say: "GIMP is about colors, 
not numbers."


>> 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.
>
> This would be ridiculous - by misinterpreting the device dependent colors you
> would be applying visual adjustments that differ between images, rather than
> being the same. The fact that you have applied uniform changes to the device
> values is not what you want, since the device values have different meanings
> for different device colorspaces.

OK, here i'm silently presuming that GIMP is fed with absolute color data 
(meaning
that the device color profile is known in case device dependend colors are 
given).

I consider working with device dependent files (that is, without knowing the 
profile)
a very special case -- that would be like GIMP in 'number mode' instead of 
'color mode'.

As you have explained before, it is necessary to be able to export device 
dependend files [1],
but i wonder if GIMP really needs a special mode to deal with device dependent 
colors other
than on import. I mean, if the device color profile isn't known, the data can't 
even be displayed
without getting misinterpreted, left alone proccessed.


But i don't quite understand:

 > This would be ridiculous - by misinterpreting the device dependent colors you
 > would be applying visual adjustments that differ between images,

why am i automatically misinterpreting the device dependent colors?
If the device color profile is known, the conversion to scRGB should do no harm.


 > The fact that you have applied uniform changes to the device
 > values is not what you want, since the device values have different meanings
 > for different device colorspaces.

how could one apply uniform changes 'in meaning' if the device color spaces are 
unknown?


regards,
yahvuu


[1] https://lists.xcf.berkeley.edu/lists/gimp-developer/2010-March/024386.html
     .. and shame on me i missed to send a 'thank you!' for pulling things 
straight in that mail.
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