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: Wed, 13 Nov 2002 18:44:05 -0800
At 4:15 PM -1000 11/13/02, Steven Kornreich wrote:
Well I did this test. I open a new document in PS7, assign my scanner
profile, make a box 255,255,255 and then convert to printer profile. And
there I get the "scum dot" The only way I can get no scum is go from
scanner - adobe ws (adobe rgb, DonRGB) - printer profile. My question is
when I first assign profile, then convert to working space like adobe rgb or
donrgb, I knotice that all my rgb values change, but the cmyk remains the
same. So what is happening? When converting to workspace, is PS changeing
the color?
Well, the whole idea of color management is to change the numbers in
such a way that the color appearance is preserved. So when you
convert from scanner RGB to ws RGB, the numbers must change if you
want to preserve the appearance.
When I do the conversion from scanner to WS, I use ACE, Relative, and Black
point on, Is this the way to go?
Generally, yes. If the scanner profile actually supports the
different rendering intents, perceptual or even saturation may give a
more pleasing result on some images, but relcol + BPC will be closest
to what's on the film.
Ideally, you want to do the conversion from scanner RGB to ws RGB in
high-bit mode. If the scanner lets you scan to a specific RGB ws, you
can do that if you want to avoid the overhead of high-bit files. I
usually bring raw high-bit scans into Photoshop, but I'm not in a
high-volume production environment.
It sounds like the scanner profile is the culprit. What happens when
you convert scanner RGB 255, 255, 255 to LAB?
Bruce
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