[argyllcms] Re: argyllcms Digest V14 #71

From: <ldasignup@xxxxxxxxx>
To: <argyllcms@xxxxxxxxxxxxx>, "argyllcms digest users" <ecartis@xxxxxxxxxxxxx>
Date: Tue, 25 Jul 2017 19:26:55 -0600

Hi Graeme,

Sorry, but pretty much 100% of your reply below is "over my head".

Can you provide a link to the files, including the printer ICC profile ?

I'm not sure which files. The .tif of the test print with 186 patches? Jpg? The actual .icc profile? Other (besides what I've already sent to your)?

Thanks for your excellent support of Argyllcms.
Lynn

------------------------------

From: Graeme Gill <graeme@xxxxxxxxxxxxx>
Subject: [argyllcms] Re: Getting mediocre D-max with Canon iB4020 pigment print
Date: Fri, 21 Jul 2017 14:18:11 +1000

ldasignup@xxxxxxxxx wrote:

Hi,

I'm wondering if it is a misconception on my part that the D-Max of a RGB(0,0,0) profile
patch using ACPU (Adobe Color Printer Utility) and a test print with a RGB(0,0,0) patch
should be more or less equally dark.

You'd hope that input RGB=0 maps to a reasonable point in the printer
colorspace, but it's always possible to be surprised by what
the linker in combination with its options and the profiles is doing.

My work-flow to evaluate profiles for D-Max:
* Make profile using 4 sheets with total of 4464 patches
* Make note of the L*a*b value for the RGB(0,0,0) patch
* Make test print including 186 patches for X-Rite i1iSis to scan.
* These patches include the 24 colors of the ColorCheckr,
   about 100 gray patches from black to white, and
   about 60 different flesh tones.
* FWIW, I've got scripts to evaluate the overall DE2k,
   and also the ColorCheckr patches as a sub-group,
   the gray patches as a sub-group, and the flesh tones.

With dye printers such as my Canon Pro-100 with CLI-42, iP4500 with CLI-8, and MP990 with
CLI-221, the RGB(0,0,0) patch of the ACPU print are quite close in D-Max to the test print
that also has nine RGB(0,0,0) in a 3x3 "super-square".

But with my pigment CMYK Canon iB4020, the D-Max of the ACPU RGB(0,0,0) patch is
significantly and measurably blacker than the test print using the printer profile. That
suggests to me that the printer+paper+ink is capable of D-Max in the range of Lab 5, but
the print using the printer profile comes short of that. Operator error on my part?

It comes down to checking the printer profile B2A and linking workflow.

1) What is the best output of the printer B2A and what PCS(s) does that
correspond to ?

2) Does the workflow map the input space RGB=0 to a PCS that gives the best output ?

Below is a test print with 186 patches (not color managed as an embedded file). It
probably won’t show up for readers of the list ... sorry.

Can you provide a link to the files, including the printer ICC profile ?

Cheers,
Graeme Gill.

[argyllcms] Re: argyllcms Digest V14 #71

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