In article <390### [at] aetecee>, Vahur Krouverk <vah### [at] aetecee> 
wrote:

> I'm currently implementing color space conversion for my shader patch.
> It includes conversion between rgb, xyz, xyY, hsv, hsl and yiq spaces.
> It seemed to be good idea to put this conversion function to color.c
> file (err, coloUr.c). Now I'm wondering,  whether it is good idea to
> make those conversion functions available from POV-Ray as well? Is there
> any use for them? One thing, that comes to my mind, is post-processing:
> with conversion from rgb to hsl (or hsv) it would be easy to add or
> reduce saturation, or change hue.

I have been wondering about making these conversion functions for a long 
time, the only thing stopping me is a complete lack of knowledge of 
these color spaces and converting between them. I have also been 
thinking a post_process filter which does this would be useful.


> If this is good idea, then how should it be implemented? As functions?
> Which form would be preferable:
> rgb2hsv(COLOUR) or 
> COLOUR rgb2hsv(COLOUR)? 

I would definitely choose the second syntax, the first would only cause 
trouble. The function should take and return a color.(I used a vector 
function for eval_pigment(), so it doesn't return an actual color. That 
means it loses filter and transmit, but I didn't know how to add a new 
class of functions which returns a color.)
The post_process versions wouldn't require any parameters.

A somewhat similar set of functions would be functions for conversion 
between cartesian, cylinderical, and spherical coordinates.

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://chrishuff.dhs.org/
TAG Web page: http://tag.povray.org/

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