Re: Color and ColorSync in Mac OS X
Re: Color and ColorSync in Mac OS X
- Subject: Re: Color and ColorSync in Mac OS X
- From: Dave Camp <email@hidden>
- Date: Wed, 10 Jul 2002 08:22:17 -0700
on 7/10/02 5:00 AM, John Zimmerer at email@hidden wrote:
>
OK, time to wade in.
I was hoping you would show up! :-)
>
Specific to the printing system, if you are trying to print targets from
>
Preview, you can tag source data with the destination profile to force a
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null match.
This is expected.
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ColorSync will match source data to whatever the driver provides. Some
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drivers hand up a color space (e.g., HP hands us sRGB and they take it
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from there). Some drivers hand up device profiles (e.g., EPSON when
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using ColorSync color matching). Some drivers hand us nothing, in which
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case we match to a rather generic profile. More info on this when we
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release Jaguar. This is what happens in the EPSON drivers when you turn
>
off color management. This effectively mirrors the Mac OS 9 raster
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printing experience.
Correct me if I'm wrong, but you seem to be agreeing here that whatever is
being printed is ultimately converted to some color space (either provided
by the printer, or a generic space if noting else). There is no pass through
mode, which is what I've been told in the past by the printing folks.
>
In the case of profiled CMYK source data going to a raster driver, we
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match (i.e., convert) from the source profile to whatever profile the
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raster driver hands us (see above). In the case of untagged CMYK source
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data, in Mac OS X 10.1.5 and earlier, we use a one-minus rule and
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effectively treat the data as RGB. Life is different in Jaguar. Can't
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say any more yet.
So, a CMYK document, going to a CMYK inkjet driver has a path like
CMYK->RGB->CMYK?
>
In the case of /DeviceCMYK, we have no idea which device or how it
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"thought" of CMYK. We use the user-supplied Default CMYK profile from
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the ColorSync preferences. Actually whenever we encounter a Device space
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we use the corresponding ColorSync preference. So /DeviceRGB will be
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tied to the Default RGB profile.
I've observed this...
Thanks,
Dave
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