Re: Application of ICC profiles.
Re: Application of ICC profiles.
- Subject: Re: Application of ICC profiles.
- From: Chris Murphy <email@hidden>
- Date: Sat, 6 Jan 2001 12:25:31 -0700
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At what point are ICC profiles actualy activated? ie when are the profiles
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used to alter the image data during the postscript/RIPping process.
The main thing to keep in mind is that the most common classes of ICC
profiles are device profiles: monitor, input and output. These kinds of
profiles necessitate TWO for any kind of conversion. So you can't
actually use only one (other than embedding into an image, which doesn't
actually do anything to the image).
I would stay away from PostScript color management. That is a real bear.
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What is the difference between selecting the postscript colour matching
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option and the ColorSync colour matching option in the Laserwriter print
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driver?
PostScript Color Matching is used when you are printing from an
application that generates its own PostScript. Examples are PhotoShop,
QuarkXPress, Illustrator, InDesign - etc. This means you need to know
which apps make their own PostScript before you can effectively use this
option. The result is this option includes a Color Rendering Dictionary
(CRD) into the print stream generated by the application, and tells the
RIP to convert images based on CSA's (source profiles) and CRD's
(destination profiles).
ColorSync Color Matching is used when you are printing from an
application that doesn't not generate it's own PostScript. The
application generates QuickDraw, and this option has ColorSync doing
color space conversions at the workstation level on that QuickDraw stream
- then the modified stream is processed into PostScript by the driver and
Mac OS, then sent to the printer.
The whole process of driver level color management is frought with
problems. It is possible to do this a lot easier in applications that
don't do *any* form of color management at all, and do not generate their
own PostScript. This is because it can be safely assumed that the monitor
profile is source, and the destination profile is the printer you're
using. The monitor profile is assumed automatically (as the System
Profile or Display Profile depending on which version of ColorSync you're
using). So all you have to do is set the right destination profile in the
driver (this is the profile for the inkjet printer) and then hit print.
Again, working with PostScript color management is something I would stay
away from. Each RIP has its own implementation. Some ignore RGB CSA's but
not CMYK CSA's, or vice versa. So you can get different results.
QuarkXPress won't even generate CSA's so you're SOL trying to use
PostScript color management with that application. It's just not worth
the effort until you have a really good grasp on color management in
general; and then have a huge amount of spare time on your hands.
Chris Murphy