[argyllcms] Re: Gamut mapping problems in 1.1.0
- From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 12 Nov 2009 20:22:57 +0100
Idea Digital Imaging wrote:
The debate of re-target/re-purpose is interesting though. In my case I
operate in the "ambiguous" category. The original images have been
extensively retouched in an RGB working space and nobody would want to
refer back to the original scene :)
This means that the separation for proof/print can be a mixture of
re-purposing/re-targeting.
I know what you mean as I'm in similar situations frequently.
A good example might be the development of a key visual for a brand or
an advertising campaign.
If the job is running well, we get RGB TIFs together with RAW files from
the photographer. The RGB TIFs are the photographer's interpretation of
how the image should look on an ideal medium and they are normally
already cleared with the customer on screen (usually already in the
photo studio during or subsequent to the shooting). The RAW files are
kind of backup or safeness if something went wrong in the initial
processing or if the customer has second thoughts. But already the
"original" RGB TIF is ambiguous: we can never be sure to see what the
photographer and the client saw (as long as we are not sit in on the
shooting/clearance). What they saw is the image in the RGB working space
clipped to the display gamut. It strongly depends on
- the gamut of the photographer's monitor
- the viewing conditions in the studio (often very dark)
- the state of adaptation of the viewers
- the quality of the display profile
So the question is always: did they see what we see? Is e.g. the
oversaturated red we see intentionally or did they see a clipped
version? Is the clipping /we/ see intentionally? Did they desaturate the
greens intentionally or enforced by the gamut limits of the equipment (I
don't want to consider the Photoshop skills of the photographer as
another possible limiting factor for the moment ;-)
The next input are the creative ideas of the advertising agency
involved. Our struggle consists in brining together the parts and ideas
an to merge them to something thats actually printable -- often for a
variety of different media like sheetfed and web offset, various flavors
of gravure printing, digital large-format printing on all kinds of
substrates and -- far the worst -- Newspaper.
The first tuning phase takes place by means of proofs for /one/ printing
condition -- almost always FOGRA39 / ISO coated v2. The Photoshop file
always stays in the RGB working space and the operator has to switch
between the normal display, ISO coated v2 softproofs and softproofs for
other important printing conditions.
At the latest when the point is to adapt the approved ISO Coated v2
proof to other printing conditions, the pipe dream of a "media
independent" ICC workflow goes up in a cloud of smoke. Normally we end
up with an master RGB Photoshop file with a bunch of layer sets on top
of the virtual composing -- one set for each printing condition. It's
not that the main purpose of these correction sets is to compensate for
the different gamuts of the printing processes, but for the flaws and
quirkinesses of the respective output profiles and the variations
between vendor depended gamut mapping strategies. We have to stick with
these output profiles as they are branch standards and the recipients
expect (rightly) PDF/X files with the respective profile embedded as
well as separations that correspond to the embedded profile.
A consistent, decent gamut mapping combined with the chance to "copy"
the separation behavior of a given profile is the key to improve this
unfortunate situation substantially IMHO. And Argyll is on a very good
way to provide both.
So: congratulations, Graeme -- the upcoming release will be a great leap
forward once again :-)
Klaus
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