[argyllcms] Re: Fakeread with cmyk profile...

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 20 Feb 2009 13:00:27 +1100

Auke Nauta wrote:
I do not have any chart readings of this profile, nor are they embedded.
The actual blackpoint of the device is approximately 10.5,1.5,1.0 (Lab).

Right. Does the profile have a black point tag that has this value
in it ?

So I use:
* targen -s17 -g33 -e8 -d4 -f4092 -I -cMy_CMYK_Profile.icc target (.ti1)
* fakeread -l -b0,0,0 My_CMYK_Profile.icc target (.ti3).
* colprof -v target (.icm).

Now the thing is that *some* scaling is going on depending on the -b
parameter during fakeread, but the actual blackpoint is *never* lower than
the initial 10.5.

I'm at a loss here!

My guess is that the profile has no black point tag, so the ICC default
of 0,0,0 is used instead. Since you've set a black target of 0,0,0, nothing
changes.

[ The next release will take a somewhat smarter approach, and determine a
  black point if the profile is missing the black point tag. ]

Graeme Gill.


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