On 12.08.2010 12:52, Rupert Weber wrote:
> Thanks a lot for all the input.
> I have been using the matrices from
>     http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html *)
> and thought I was doing sRGB/D65-to-Lab or sRGB/D50-to-Lab.
> But as I understand now, I was actually doing sRGB-to-Lab/D65 or /D50;
> while all the RGB spaces like AdobeRGB or sRGB have their own fixed
> implicit reference white.
> Correct?

if you took gamma into account, then yes.

> *) This is where the matrix used by babl and the Decompose plug-in is
>      listed as "PAL/SECAM")

Never heard about that one, but that doesn't mean much :-)

> As to babl and the Decompose plug-in: They should be updated to use sRGB
> conversion?

Regarding BABL: i've had a look at extensions/CIE.c and found conversion 
using linear light RGB with the sRGB primaries and white point -- that is scRGB.
Everything fine here.

Now i'm not familier with BABL -- possibly i've checked at the wrong routines?

Regarding the Decompose plug-in:
yes, that seems to use the PAL stuff. However, i'd be surprised if that makes
a really big difference. What's more important, is that i couldn't find any
routine which respects the gamma curve defined by sRGB.

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