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From: Fernando Cacciola (fernando_cacciola_at_[hidden])
Date: 2006-11-01 08:54:36


Joel de Guzman wrote:
> Fernando Cacciola wrote:
>
>>Joel de Guzman wrote:
>>
>>>Joel de Guzman wrote:
>>>
>>>
>>>>Matt Gruenke wrote:
>>>>
>>>>
>>>>>Joel de Guzman wrote:
>>>>>
>>>>>>I disagree. A color space is a tuple of numbers. It is concerned with
>>>>>>data and layout as far as I can see. That is the very definition of
>>>>>>"tuple".
>>>>>>
>>>>>
>>>>>That's a color (or pixel value).
>>>>>
>>>>>A color space provides the semantics of these numbers, possibly
>>>>>including how they are converted to other color spaces. This may
>>>>>include its basis, CIE primaries, transfer function, gamut, etc. (For
>>>>>more information, here's a good starting point:
>>>>>http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html )
>>>>>
>>>>>A pixel format establishes the mapping between channels of an image
>>>>>(i.e. color, pixel value, etc.) and components of a color space.
>>>>
>>>>Now I see the confusion. There are overlaps in the definition of
>>>>colors and color-spaces of course. Did you think they were orthogonal?
>>>>See: http://tinyurl.com/18r for the definition of color-spaces.
>>>
>>>tinyurl mistake again! One more try:
>>>
>>> http://tinyurl.com/veebq
>>>
>>>Regards,
>>
>>That very same wikipedia article may be used to explain why Matt and I
>>are against using the term "color space" for the GIL element under
>>discussion.
>>If you read it carefully you can see that the "tuple of numbers" is a
>>"color model", not a "color space" (a mapping function binds the model
>>with the space)
>>Reading further down you see that it refers to "RGB", "CYMK", etc as
>>color models, not color spaces.
>>
>>So at most I would say that the correct term is color model. It
>>certainly isn't color space and that article shows why quite well.
>
>
> No!
>
What no exactly?

> Color space is gamut (footprint) + color model.

Right, and this is in contradiction with? (from what I wrote)

Anyway, as you know by now my problem was the tag. I wouldn't mind
speaking of color spaces in the context of the pixel<> class (which
plays the role of a color<> class).
Although in that case I would add a side note in the docs explaining
that instances of the class represents "points" in the color space
rather than the color space itself as a whole (something which could be
represented by a class, but isn't in the case of GIL)

Fernando Cacciola


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