[argyllcms] Re: Manual channel limits doesn't work in printcal for RGB-printer

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 16 Dec 2009 17:30:14 +1100

Nikolay Pokhilchenko wrote:

Nikolay Pokhilchenko wrote:


V1.1.0_RC1, Windows Vista:
When calibrating an RGB-printer, it's impossible to achieve the "darkest" black 
R=B=G=0
in the calibration result if the printcal have select the other limits. Even if I use "-x r 100", 
"-x g 100" and "-x b 100" keys.
Try my printer example attached.

The workflow:

targen -v -d2 -f0 -m0 -e9 -s274 Lin
printtarg -v -ii1 -A0.6 -a0.8 -m0 -L -T360 -p240x225 Lin
chartread -v -a Lin
printcal -v -p -i -x r 100 -x g 100 -x b 100 Lin

If You try "printcal -v -p -i Lin", the curves will be the same.

If I print the next targets by printtarg with -K"Lin.cal" function, the R=G=B=0 
output TIFF level isn't achievable. So there is heavy gamut restriction from the black 
side.


In RC2 The problem is still here. Even with 100% user channel limits in 
printcal, the
printtarg result didn't translate R=B=G=0 to zeros. For example, the RGB=0,0,0 
after printtarg
with calibration become 0,21,0. It's heavy restriction for RGB-printer gamut. 
So printcal for
RGB printer is useless.
The problem is in printcal itself.
The example device profile (one A2B only) is attached.


Sorry, I can't reproduce this. I'm using fakeread instead of 
printtarg/chartread,
but even using a couple of different RGB printer profiles in fakeread, I get
calibration curves that go fro, 0 to 100%, and produce subsequent profile
charts that have R=B=G=0 for black.

Perhaps you had better send me your Lin.ti3 file ?

Graeme Gill.

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