packages have
an option to preserve the original gamut mapping while
letting you change the black generation.
Certainly, the gamut mapping is different in different
profiling-programs and in different profiles with different black
generations. Standardized mapping does not exist. Then that means
"original gamut mapping"? But the right to impose perceptual mapping
on the sourse profile and not on the destination profile - the result
is better. Of course if the source profile contains perceptual table.
Tristimulus RGB (usually source) has no perceptual table
unfortunately, and perceptual mapping of ECI destination profiles is
not the best.
2014-10-28 22:02 GMT+03:00 Richard Falk <Richard.Falk(a)efi.com>om>:
Just use standard profiling packages and use the
profile or better yet the
original data characterization dataset (either from a separate file or
extracted from the "targ" tag in the profile) as an input. Such packages
will let you re-separate with black generation strategies that you desire.
The downside is that the gamut mapping will also likely be changed because
the recreation of the B2A# tags usually changes not only the black
generation but the gamut mapping as well. I don't know of any profiling
packages have an option to preserve the original gamut mapping while
letting you change the black generation. Technically this could be done,
but I don't know if anyone is doing that.
Thanks,
Richard Falk
Electronics for Imaging
On 10/28/14, 11:21 AM, "Alexander Konovalenko" <alexkon(a)tonkayagran.com>
wrote:
Hello,
How can one recreate the ECI ISO Coated v2 profile with different
black generation strategies?
Here is the reason why I want to do that. I prepare color separations
of RGB images for offset presses. I just use Photoshop's Convert to
Profile command with the relative colorimetric or perceptual intent
(depending on the image). I like the saturated colors produced by the
ECI ISO Coated v2 profile, as well as by the Adobe Coated FOGRA39 (ISO
12647-2:2004) profile. But there are a couple of annoying issues that
could be solved by adjusting black generation.
1) Suppressing black generation in skin tones (highlights to midtones)
and using cyan instead. Deep shadows should keep having full black.
Skin tones without the black ink tend to look better, especially under
suboptimal printing conditions.
2) Maximizing black generation. That's useful in two cases. First, for
black-and-white and nearly black-and-white (slightly toned)
photographs. When the images must use rich black for deep shadows, one
cannot resort to using only the black ink. Second, for colored line
art that for some reason came in raster form. Thin dark lines must be
separated with maximum black generation to alleviate any
misregistration on press.
Also, sometimes it is necessary to adjust total area coverage for an
otherwise perfect color profile.
Photoshop's custom CMYK profile functionality appears to shrink the
gamut of the resulting profile without any good reason. According to
Adobe's Chris Cox, that feature is obsolete and can't be used to mimic
the FOGRA39 profiles.
https://forums.adobe.com/message/6874119
What tools can I use to solve the above issues? Where do I start? What
tools do you use to prepare and generate FOGRA-compatible ICC
profiles?
I would appreciate any pointers to relevant information.
Best regards,
Alexander Konovalenko
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