[argyllcms] Re: profile -S -g
- From: "Gerhard Fürnkranz" <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 24 Apr 2008 19:15:39 +0200
-------- Original-Nachricht --------
> Datum: Fri, 25 Apr 2008 02:13:16 +1000
> Von: Graeme Gill <graeme@xxxxxxxxxxxxx>
> > profile -S 'ISOcoated_v2_eci.icc' -cpp -dpp solventLFP
> >
> > I get *heavy* clipping when using the perceptual intent.
>
> That's most surprising. The source gamut is obtained from
> the colorimetric A2B table. It should not be subject to any
> gamut mapping, and should represent the true gamut of the device.
Graeme,
I guess the problem is the black point which you are assuming for the _PCS_.
V2 does not define a reference medium black point for the PCS, so we cannot
rely on any standard here, but my impression is that most V2 profiles generally
assume a PCS black point of L* = 0. I.e. the perceptual intent of most
(non-Argyll) V2 profiles I've seen did map L* = 0 in the PCS to the actual
media black, and L* = 100 in the PCS to the actual media white [and vice versa
in the A2B0 table].
As long as e.g. sRGB or AdobeRGB are used for "-S", the assumed PCS black point
of your profiles will be L* = 0 as well, and everything is fine. But if e.g.
ISOcoated is selected as "-S" profile, then you assume the ISOcoated BP [which
is > 0] as PCS black point, making your profile incompatible with other source
profiles which assume a PCS black point of L* = 0 [and if you nevertheless
combine them with perceptual intent, the result will be clipped colors].
Regards,
Gerhard
--
Psssst! Schon vom neuen GMX MultiMessenger gehört?
Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger
Other related posts:
