Re: Color Navigator 4.1 - L*
Re: Color Navigator 4.1 - L*
- Subject: Re: Color Navigator 4.1 - L*
- From: Roger Breton <email@hidden>
- Date: Tue, 25 Oct 2005 07:22:36 -0400
Graeme,
There isn't anything in what you outlined that relate to RGB?
We all know that Luminance (Y) is related to RGB through some power or 1D
LUT or spline function. But in the case of L*, there must be some
intermediary variable that allow transforming back and forth between RGB and
Y first? Unless they convert straight to L* from RGB?
> Umm - L* is the L as in L*a*b*. It's a standard. No-one needs
> to licence anything ...
>
> Y as in XYZ (range 0 .. 1.0):
>
> if (Y > 0.008856451586)
> fy = pow(Y,1.0/3.0);
> else
> fy = 7.787036979 * Y + 16.0/116.0;
>
> Lstar = 116.0 * fy - 16.0;
>
> Graeme Gill.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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