[argyllcms] Re: Getting mediocre D-max with Canon iB4020 pigment

  • From: <ldasignup@xxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>, "argyllcms digest users" <ecartis@xxxxxxxxxxxxx>
  • Date: Sat, 12 Aug 2017 13:58:19 -0600

Hi Graeme,

I took a closer look at the .txt files, and noticed that while the RGB(0,0,0) patch wasn't all that dark, other patches like RGB(0,0,16) would be significantly lower, and near the D-Max of the RGB(0,0,0) patch measured from the ACPU target.

The profile seems less than linear for the really dark patches. I wonder if that is related to using pigment ink rather than dye ink? Could metamerism be involved? My older i1iSis doesn't have the UV filtering option.

With a test having 1088 patches, and read with ColorPort using my i1iSis, I sorted the 1088 lines by lowest Luminosity value. Following is typical example (Canon Ink with Canon Platinum paper) of the first 8 values per patch:

NUMBER_OF_SETS    1088
BEGIN_DATA
##ID   ID      R    G    B     L          a         b
417    417    0    0    16    6.98    -1.27    -8.4    ...
418    418    0    0    24    7.69    0.67    -15.45    ...
419    419    0    0    32    8.82    1.4    -21.66    ...
420    420    0    0    40    9.78    3.71    -27.53    ...
421    421    0    0    48    11.4    4.15    -31.6    ...
349    349    9    0    9    11.48    3.72    -2.61    ...
348    348    8    0    8    11.9    3.4    -2.17    ...
416    416    0    0    8    12.05    -0.68    -2.37    ...
347    347    7    0    7    12.3    3.01    -1.77    ...
415    415    0    0    7    12.44    0.26    -2.11    ...
346    346    6    0    6    12.6    2.69    -1.05    ...
247    247    9    0    0    12.77    5.11    -0.1    ...
414    414    0    0    6    12.97    0.36    -0.95    ...
246    246    8    0    0    13.01    4.42    -0.12    ...
345    345    5    0    5    13.19    2.59    -0.87    ...
413    413    0    0    5    13.29    0.87    -0.85    ...
344    344    4    0    4    13.34    2.45    -0.06    ...
245    245    7    0    0    13.46    4.07    0.35    ...
244    244    6    0    0    13.47    3.4    0.26    ...
412    412    0    0    4    13.66    0.99    -0.1    ...
343    343    3    0    3    13.66    2.11    -0.01    ...
243    243    5    0    0    13.69    2.97    0.51    ...
342    342    2    0    2    13.71    2.22    0.58    ...
382    382    0    8    8    13.72    -3.22    -0.56    ...
383    383    0    9    9    13.76    -3.79    -1.08    ...
380    380    0    6    6    13.8    -1.47    -0.05    ...
.....
6        6        0    0    0    14.11    1.62    0.86     ...
4        4        0    0    0    14.13    1.53    0.84     ...

Note that the line for the RGB(0,0,0) patches at the end have L(uminosity) of over 14.

I'll look at patches for a dye printer like the Pro-100 to see if it handles really dark patches in a more linear way.

-----Original Message----- From: ldasignup@xxxxxxxxx
Sent: Tuesday, July 25, 2017 7:26 PM
To: argyllcms@xxxxxxxxxxxxx ; argyllcms digest users
Cc: Graeme Gill
Subject: Re: argyllcms Digest V14 #71

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

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  • » [argyllcms] Re: Getting mediocre D-max with Canon iB4020 pigment - ldasignup