[argyllcms] Re: Optimizing Printer Profiles
- From: "Nikolay Pokhilchenko" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "nikolay_po" for DMARC)
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 10 Jul 2017 23:14:19 +0300
Понедельник, 10 июля 2017, 22:27 +03:00 от "Alan Goldhammer"
<dmarc-noreply@xxxxxxxxxxxxx>:
My monitor is a wide gamut NEC and re-profiled every four weeks. I’m seeking
to prepare the best profile for printing that I am able to do so using Argyll.
You shouldn't miss two different tasks: A) to achieve best numerical profile
accuracy and B) to get best gamut mapping when required.
With fine instrument and stable printing you may be able to to fit printer
profile into better than dE2000 difference after several attempts. This will be
stage "A". This is standard task for any color profiling software. The result
of this stage is a pair of conversion tables sets - absolute and relative B2A
and A2B three dimension lookup tables. These tables are fully characterize the
color capabilities of certain print mode on certain media by certain inks.
Nothing else is needed to characterize your printing process more (I don't say
about an effects like a gloss, metallic, fluorescence and other special effects
and phenomenons outside of ICCv2 specification).
The feature you've asked about initially, the gamut mapping source setup, is
different thing (B). It is optional for device profiling. Moreover, in my
opinion it is not a device profiling at all. It is just an image-to-reproduce
preparation feature ant it can't solve the task of "best printing" for all the
cases. It is useful for small workshops and home use where unexperienced user
wants simple prints of reasonable quality, but not "the best ever possible".
Right now, my profiles in general are superior to what manufacturers provide
on their websites for my specific Epson printer. The question about workflow
came up after the CHROMiX profile for the new Red River paper showed such a
dramatic difference. This was commented on by a number of photographers whose
work I know well and also the person that runs the Aardenburg print permanency
test program. The goal as you note is color accurate reproduction from the
edited image that I prepare.
Your custom profiles may be superior. But them may not be the best until you
switch the workflow to individual image or image set gamut mapping when needed.
In some cases when the images are fully inside of printer gamut only minor
viewing conditions mapping may be applied (and may be not applied) for best
results. No gamut compression is needed. So with wide gamut printing process
sometimes you needn't the gamut mapping at all. And use of -S"sRGB.icc" or
-S"AdobeRGB1998.icc" is justified only for compatibility reasons for users who
wants simple printing from sRGB sources. You needn't make an accent at -S
parameter of colprof. Just build a profile with standard sRGB mapping as
recommended.
Perhaps I was not clear enough in the original post regarding the ultimate
gamut properties of the printer which are greater than sRGB but less than
ProPhoto. Ultimately it comes down to color workspace but as noted, I’m using
Lightroom which has its own contraints.
I'm recommending you to play with device links. Use your custom precise profile
just as device character. Do not use general profile internal perceptual or
saturation mapping which is too generic - clipped if sRGB or overcompressed if
AdobeRGB1998. Build personal image gamut for each image or image set of one
theme. Then build image device link using your general profile just a color to
channel conversion reference. Use image gamut, image color space profile and
destination profile as collink input data. Set viewing conditions, choose gamut
mapping intent. Then convert your images right from your favorite editing space
right into your printer space. You may use cctiff for that. This is a
scientific way to obtain the best prints. The best by precision of perception.
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