[argyllcms] Re: colprof and proofing purposes

  • From: Michael Schulz <ms.typografik@xxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Mon, 28 Sep 2009 20:32:37 +0200


this is a lot of new stuff for me. Considering myself as someone how makes
his first steps in the jungle of profile creation. Nevertheless I'm ready to
learn. If I understand you right, you are talking about the per channel
limits scaled by the RIP for the linearization. I have to see the printer's
behavior and would like to contact you again in this case ­ I'm not sure if
I really understood your example for the yellow channel... The risk of
damaging the printer by total ink limit override could be real, because the
printer is an old one (HP DesignJet 10 ps). Will take a while before I find
the time to print out and measure targets.

Thank you

Am 28.09.2009 17:54 Uhr schrieb "Nikolay Pokhilchenko" unter

> Michael, my advice is "IMHO". There may be another opinions and experience. :)
> It's would be normal to profiles to be compute with -qu quality in 20-40
> minutes for RGB and till several hours for CMYK.
> One more IMHO: You should avoid the channel and channel mix clipping by RIP
> ink limit control. It will the best if per-channel limits will be scaled to
> 100% without saturation. For example yellow channel ink limit 80%:
> Y=50%in => Y=40%out
> Y=80%in => Y=64%out
> Y=100%in => Y=80%out.
> If the RIP limits the channel with saturation, like this:
> Y=50%in => Y=50%out
> Y=80%in => Y=80%out
> Y=100%in => Y=80%out,
> the profiler will work harder with the saturations. The unwanted transitions
> on image gradients may appears at the limit point.
> It would better to set total limit in the profile (colprof -l 360), nor in the
> RIP. If the printer can not be damaged by accidentally total ink limit
> override, I'm preferring to set only linearizion with per-channel limits but
> turn off total ink limit in RIP.
> This approach gives the profiler the best condition to work.
> One more IMHO: when the good linearization is achieved and total ink limit is
> defined, You should print the Argyll targen generated targets with the defined
> TIL+10%, nor the standard ISO targets. If target TIL will be closer to
> desired, You'll get more useful patches in the area of interest. The patches
> behind Your practical TIL will be almost useless. Especially if You'll not try
> to predict printer behavior behind printer TIL.

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