[Gimp-developer] HSL Color Picker

[Øyvind Kolås]

On Sun, May 31, 2009 at 10:36 PM, Robert Krawitz <rlk at alum.mit.edu> wrote:
>   Omari Stephens wrote:
>     - This requires more computation to use because of the "odd"
>       shape of the space of valid coordinates.  That is, not all
>       valid coordinates are valid colors.
>
> What I don't like about this is that it leaves a large fraction (well
> over half) of the color space unused and functionally meaningless.  I
> agree that this representation is more accurate, but functionally it
> seems more difficult to work with.  Think about the UI implications.
>
>     - HSL and HSV are in wide use, and this is neither HSL nor HSV
>       (though it's just a coordinate transformation away from both
>       HSL and RGB)
>
> It's a simple coordinate transformation from HSL:
>
> H' = H
> S' = S * (1 - ((|L - .5|) * 2))
> L' = L
>
> but it's not any simpler than RGB->HSL.

The colors selected in this manner will likely be used in a different
color space than the one they are selected in anyways. This means that
undefined regions of the colorspace and computational complexity are
only a concern of the color picker interface. CIE Lch is another
options that can be considered. I haven't studied it but suspect that
the current computation of Lightness has crude 8bit/gamma assumptions
in it.

/Øyvind K.
-- 
«The future is already here. It's just not very evenly distributed»
                                                 -- William Gibson
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