[argyllcms] Re: Post-editing white and black point of a icc-profile
- From: Alexey Gribunin <Gribunin@xxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 15 Jan 2014 11:45:57 +0400
Hello Daniel!
Sometimes I have the same need to adjust black and white points.
If Graeme will release his tool for accurately shift of substrate color
by spectral reflection decomposition then it would be great!
Now I make it directly in Lab measurements in EXCEL BEFORE icc profile
creation.
I adjust L-value of black and white points by scaling it in EXCEL with
broken curve from original value to the needed one. At the same time the
medium tone L values stay the same, let's say from L 30...40 till
60...70 (The curve is adjustable, I can choose these values). A and B
values also stay the same.
If you need to adjust the COLOR of white point and to put it to all
profile tables, then it's little bit tricky. You can do it in two step
way - create icc profile, change WP Lab values in ProfileEditor, convert
CMYK testchart to Lab with fakeread (or with ColorLab) with Absolute
Colorimetric RI, then create icc profile again.
Another way (even more tricky) is to edit measurements in EXCEL with 3D
table. Black point color also can be changed with 3D table.
Best regards,
Alexey Gribunin, UNIT Color Technologies, Moscow, Russia.
From my point of view, an option to manually override the printer
profiles white point with a defined value would be very welcome. Even
just to reduce the source-white-simulation in images converted for
absolute intended output.
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