[argyllcms] Re: negative primaries

  • From: Gerhard Fuernkranz <nospam456@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 10 Jun 2010 22:54:06 +0200

Am 07.06.2010 04:29, schrieb Graeme Gill:
> It would be interesting to see if non-Luther condition cameras
> routinely produce such imaginary XYZ values for highly saturated
> source colors. If so, then the ICC's advice to clip such colors is
> probably not so good...

Well, Graeme, it's actually not the camera which produces XYZ values
outside the visual gamut (including negative ones), but eventually it is
always the matrix. If the Luther condition is met, then there exists (in
the ideal case) indeed a single "correct" matrix which is entirely
determined by the camera, but if the Luther condition is not met, then
the choice of the matrix is is a trade-off between several objectives
and evils anyway, and it is no longer the camera only, which determines
the matrix. It would be for instance certainly possibly to constrain the
matrix in order to avoid that any RGB triples inside the camera's
spectrum locus map to XYZ numbers outside the visual gamut - then we
should never end up with imaginary XYZ values, even if the captured
scene contains the most saturated colors one can imagine (i.e.
monochromatic ones).


Other related posts: