Re: Gutenprint settings for profiling ?
Re: Gutenprint settings for profiling ?
- Subject: Re: Gutenprint settings for profiling ?
- From: Robert L Krawitz <email@hidden>
- Date: Mon, 19 Jun 2006 07:10:40 -0400
Date: Mon, 19 Jun 2006 09:26:43 +0200
From: "edmund ronald" <email@hidden>
So we have it on file for the list, straight from the author's
mouth, could you please summarize the Gutenprint settings for
people intending to profile and print photos using an externally
managed CMS workflow, both in RGB and CMYK ?
1) Select the appropriate paper type and other printer settings such
as media source (input slot).
2) Select the appropriate Input Image Type (RGB or CMYK).
3) Set the Color Correction as follows:
* "Uncorrected" if you are applying a profile that assumes the output
is well-linearized (the most common case).
* "Density" if you are applying your own linearization curves, but
want to have the output value scaled for the correct amount of ink
(not recommended in 8-bit mode).
* "Raw" if you are applying your own linearization curves, including
setting the total amount of ink (not recommended in 8-bit mode).
Correct ink amounts will be *highly* dependent on resolution.
The default color correction when printing photos is normally High
Accuracy, which does cross-channel (HSL) corrections. I don't
recommend this if you're doing your own color management, but as
usual your mileage may vary. The other color correction modes that
do HSL adjustment are Bright Colors (which does the same correction
as High Accuracy but which hard clips saturation rather than
asymptotically approaching 1) and Correct Hue Only (which corrects
the hue, but doesn't adjust saturation or luminosity; this usually
achieves darker and more vivid, but less accurate, cyan-based
colors).
4) Select the "Photograph" Image Type (alternatively, select EvenTone
dither algorithm).
5) Select either the Quality or Resolution of your choice. Quality
settings (on Epson printers only) are basically prepackaged
resolution choices. For printing photos I recommend starting with
Photograph quality and adjusting it upward (to Super Photo or Ultra
Photo) only if needed. If you prefer to select the Resolution
yourself, start with 1440x720 on most printers and move up only if
you're having banding or dither noise problems.
6) Leave all other settings at their defaults.
Separate profiles must be created for each choice of paper type and
resolution or quality setting. Profiles created for the Epson OEM
drivers or other RIP's are not likely to produce good results with
Gutenprint; Gutenprint does not make any attempt to match the OEM
driver.
Dither algorithm and unidirectional vs. bidirectional shouldn't affect
color output, but I don't recommend changing them after profile
generation.
To clarify, these would be the settings which we would use to print
profile testcharts - and later to print photographs afterwards from
Photoshop with the PS color engine doing the profile-related color
conversions.
There's not much I can say about Photoshop, since I don't use it (I
want to create an entirely FOSS-based workflow), so you're on your own
for that.
Please, for both RGB and for CMYK.
--
Robert Krawitz <email@hidden>
Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail email@hidden
Project lead for Gutenprint -- http://gimp-print.sourceforge.net
"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton
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