[argyllcms] Re: Recommendations to tweak ArgyllCMS profile to open up shadows?

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 04 Dec 2014 09:35:58 +1100

Jerry Chan wrote:

> Could someone provide recommendations on how to tweak the ArgyllCMS profiling 
> process to
> open up shadows for printed output? Using Windows 7, ArgyllCMS 1.6.3 and 
> printing to a
> Canon IPF6350 with genuine OEM inks on various matte paper (Epson, Canon)

        ArgyllCMS doesn't have much in the way of tools for tweaking - the
emphasis during its development was to "do it by the numbers". What tweak
tools there are (i.e. refine) is not really meant for arbitrary manual changes.

> I have calibrated / profiled my dual monitor setup so they are a very close 
> match to each
> other. The three-quarter-tones to shadow areas printed on matte paper are 
> maybe 1 - 2
> f-stops too dark compared to the screens. Printing the same image on photo 
> glossy paper is
> much better (roughly 1/2 f-stop too dark in that region).

The fact that the glossy and mat results don't seem to match, makes the 
suspect. It's worth checking that they measure differently though, before
proceeding any further. i.e. if you print out a target black and grey patches
to both the glossy and mat, what is the L* numbers for all 4 patches ?

If it looks like the grey patch number is substantially different, and that this
is not explained by a difference in black level, then it's worth doing some
verification measurements on the mat stock to track down exactly where things
are going wrong in the profiling and printing process. This breaks down
into two steps :- 1) does the profile accurately represent the printing
behavior ? 2) Is the printing process outputting the correct device values
to produce the desired output color ?

Graeme Gill.

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