Re: Is this a scum dot?
Re: Is this a scum dot?
- Subject: Re: Is this a scum dot?
- From: bruce fraser <email@hidden>
- Date: Tue, 19 Nov 2002 15:00:14 -0800
At 6:50 AM -0800 11/19/02, Lee Varis wrote:
Perhaps Mr Fraser could elaborate on his method of profiling the
"wide-open 16-bit channel behavior" and editing to produce the
"best agreement" between actual values and predicted ones? I'm
particularly interested to see if I can find something similar for
digital camera captures.
Lee,
What's with the "Mr. Fraser" stuff? It's me, remember?
I'm not sure that what I do for scanners is translatable to digital
cameras -- I lean toward believing that it's not. Scanners have a
fixed light source, and they're capturing images that have already
been rendered to a fixed dynamic range and color gamut in the process
of capturing on film.
Rather than write a really long email, let me point everyone to
http://www.hutchcolor.com/CMS_notes.html
The document of interest is the Scanning Guide.
The way I determine the "ideal" tone curve is:
I scan the target at different tone curve settings.
I build a profile for each one (appropriately named so I know which is which).
I apply the corresponding profile to each target scan, and convert
abscol to Lab.
I compare the resulting Lab values with those in the target description file.
I choose the one that gives the lowest delta-e.
Typically, my scans come in a little flat, and a little unsaturated,
with the hues spot-on. It's very easy to optimize them from there...
Bruce
--
email@hidden
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