scanner profiling + w/b
scanner profiling + w/b
- Subject: scanner profiling + w/b
- From: "Andre Schützenhofer" <email@hidden>
- Date: Mon, 09 Jul 2001 12:58:24 +0200
Hi all,
anybody please correct me if I'm wrong, but let me assume something. I think
creating a scanner profile goes like this:
1. there's the target with a number of fields who are designed to describe
the gamut of the scanner.
2. this target is to be measured by a spectro creating data which is
dedicated to be the PCS.
3. in order to create the profile the scanned RGB-values are assigned to the
according LAB-values. That's what the LUTs are based on.
Maybe it's not that simple in particular, but basically I think that's it.
So there's just this one direction (RGB->LAB), just this one LUT and there's
no mapping, it's just called perceptual bacause it is the rendering default.
Choosing any other intend in the convert to profile dialog makes no
difference, because the other intents refer to perceptual/this one table.
Now I have one question and I could imagine this has been discussed before,
(if so it was before my time joining this list...) but in what situation is
it best to set white/black? My current procedure gives acceptable results,
but I would appreciate to hear about a better way. So here is my approach:
Profiling and scanning absolutely raw with not setting W/B (my scan-software
unfortunately does not support ColorSync). Then assigning the profile to the
scan and opening in Photoshop. Setting white/black in the scanner-gamut (I
know, scanner-gamuts are often distorted, so I use this carefully), knowing
there will be "holes" in the histogram. Then converting to my
RGB-workingspace, where the posterisation-effects are gone. I lead this back
to the CMM who interpolates the missing steps. Now the file is ready to
color finetuning and composing. The results are ok, but theres still much
interpolation involved. What about setting w/b in the raw scan and/or in the
profiling process? Due to the fact that we scan individual Images, don't I
compare apples and oranges if I do so?
It would be great to read about some experiences and/or solutions.
Thanks in advance for any hints.
Andre Schuetzenhofer
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