Re: Is this a scum dot?
Re: Is this a scum dot?
- Subject: Re: Is this a scum dot?
- From: Roberto Michelena <email@hidden>
- Date: Mon, 18 Nov 2002 10:36:49 -0500
>
It depends completely on your application. I would guess that
>
you're thinking expert scan operator with professional gear. I'm
>
thinking somewhat more generally. If you really don't
>
care about the color accuracy, then you probably won't bother with
>
trying to use ICC profiles on a scanner. Use whatever its
>
native RGB is, and and fiddle it till it looks right.
This reminds me of a very old thread which left me forever dubious of
scanner profiles.
Basically, it said a scanner has no gamut. Or at least no gamut that you can
find by scanning a physical target. It's kind of open ended, an integrating
function such as XYZ. (or does XYZ have a gamut? - I am not sure...)
Furthermore, the best scanner should not have fixed interpretation. It
should analogically tweak the capture range and/or light intensity depending
on the original being scanner, to minimize electronic noise and maximize use
of its bits. I don't know if any real scanners do so now, though.
And in most applications, yes, scanning is an interpretation not a faithful
rendering to the transparency. Why? In part because the transparency is also
an interpretation, and imperfect at that. For example the cast. Or the
illumination of the shot, to which a viewer in the scene would have adapted,
but the film didn't and neither did your scanner.
So scanning is trying to get back to the scene as you'd have seen it, not as
the film saw it.
In fact, the one important application of colorimetric scanning I can think
of, is the direct scanning of reflective art such as a painting. There
you're trying to bring a reflective flat thing to a similar medium, the
reproduction print. There should be no interpretation beyond gamut mapping,
and color appearance should be preserved to the max and in this case, color
appearance equals Lab color values because it's the same medium.
But then, I guess reflective art is better off being digitally shot than
scanned... Which brings us to profiling of digital cameras, an even larger
can of worms...
-- Roberto Michelena
EOS S.A.
Lima, Peru
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