RE: Color Management Questions (Was Profiler RGB and Silverfast)

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Let me see if I understand this. You can't _not_ select a media type, so it
appears that there is no way to really "turn off" the built-in profiles.
Therefore, even if I select No Color Adjustment in the printer properties,
and turn off Printer Color Management in the print dialog box (Win2K), an
explicit profile applied in Photoshop still has to be combined with some
sort of built-in paper-related profile. (The Media Type box isn't greyed
out.) This would mean that the profile would have to be built with a
particular media type selection in mind, and wouldn't work with a different
setting.

Some media type settings will inevitably limit the amount of ink, relative
to other paper settings, and therefore have a smaller gamut. I would think
one would have to know which paper setting dumps the most ink onto the
paper, and use that for all externally applied profiles--since the profile
can always reduce the range of numbers sent to the printer driver, but can't
increase them beyond zero to 255.

(My guess would be that Plain Paper would have the widest gamut, since it
tends to soak up ink more than coated papers. I don't mean that printing on
plain paper can produce the widest range of colors, just that selecting
Plain Paper can lay down the widest range of quantities of ink.)

I also don't "get" the printer driver color controls. I assume that
selecting sRGB means that it expects sRGB data to be sent to it. But if I
select ICM, what profile defines the color space of the data to be sent to
it? Does Photoshop normally tell the driver what color space the data is, or
what profile describes the color space? Or does Windows do this? Or does the
driver tell Photoshop (or Windows) what color space it's expecting? Or do
the program and driver each tell Windows ICM what color spaces they use, and
let ICM do a conversion between the program and the printer driver? And what
color space is used for No Color Adjustment? Some linear relationship
between numbers and dot density?

It's funny, I believe I understand color science pretty well, and I also
know software very well (I'm a programmer), but I can't figure out how color
management actually works.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

> -----Original Message-----
> From: owner-epson-inkjet@leben.com
> [mailto:owner-epson-inkjet@leben.com]On Behalf Of Matt Hagadorn
> Sent: Sunday, September 23, 2001 6:37 AM
> To: epson-inkjet@leben.com
> Subject: RE: Profiler RGB and Silverfast
>
> When ICM is selected in the driver, the paper type would
> certainly tell the
> Epson driver which of its internal profiles to use. On Windows 2000, the
> Epson unified profile is stored in C:\WINNT\system32\spool\drivers\color,
> with all the rest of your ICM profiles. For the Automatic settings, I
> couldn't say. For No Color Adjustment, nothing is done to the
> incoming data,
> regardless of paper type selected.
>
> There is no way to add to this list, but if you've got custom
> profiles, you
> don't need to. You will select the output profile in Photoshop's Print
> dialog, and set the printer to No Color Adjustment. The paper setting will
> control the amount of ink put down on the paper, and is as much a part of
> your custom profile as the ink or physical paper used.

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