Re: Is this a scum dot?
Re: Is this a scum dot?
- Subject: Re: Is this a scum dot?
- From: Graeme Gill <email@hidden>
- Date: Thu, 14 Nov 2002 14:14:36 +1100
bruce fraser wrote:
>
It sounds like the scanner profile is the culprit. What happens when
>
you convert scanner RGB 255, 255, 255 to LAB?
There are certainly many ways a profiling system might create
scanner profiles, but given the way I understand scanner profiles
are normally created and used, I certainly wouldn't expect anything
useful to be gleaned from the answer this question.
In Relative Colormetric intent, I'd expect the RGB value of the
calibration test chart paper (NOT 255,255,255) to be converted
to Lab 100,0,0.
One possible source of background color values using scanner
profiles therefore, is the paper color of the thing being scanner
not exactly matching the paper color of the scanner calibration
test chart.
The usual solutions to such a problem would be to re-profile
the scanner using a scanner calibration test chart that has
a paper color that does match the thing being scanned, or
alternately, taking the scan into some application that lets
you reset the white point of that particular scan.
Graeme Gill.
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