Re: [boost] GIL Review

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-11-01 06:56:26

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! Read carefully. Color space is gamut (footprint) + color model.

Cheers,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net