[email@hidden: Re: [email@hidden: Re: Panther drivers-No color correction?, etc..]]
[email@hidden: Re: [email@hidden: Re: Panther drivers-No color correction?, etc..]]
- Subject: [email@hidden: Re: [email@hidden: Re: Panther drivers-No color correction?, etc..]]
- From: Robert L Krawitz <email@hidden>
- Date: Sun, 21 Dec 2003 13:18:39 -0500
Here's a response I received about the RGB vs. CMYK issue (and which I
have permission to forward). It appears that an upgrade to Panther is
required to solve this problem.
------- Start of forwarded message -------
From: Richard Blanchard <email@hidden>
Here's a quick run down on the handling of color spaces in the filter
chain for Mac OS X:
Applications which spool PDF
Application draws in its chosen color spaces.
PDF spool file captures these color spaces.
For a raster printer, cgpdftoraster renders the PDF into the printer
driver's requested raster format. In 10.2 Core Graphics is an RGB only
RIP and so the bits are rendered as RGB and then converted to the
requested format. This is the RGB knothole. Even CMYK data drawn by the
application and destined for a CMYK printer driver raster format goes
through an RGB conversion.
In 10.3, Core Graphics can also render CMYK directly and so the RGB
knothole is removed. 10.3 also supports the cups color profile PPD
comments so a printer driver can request not only a raster format but
also can specify the format's color space. The user can override the
driver's color space through the ColorSync Utility.
For a PostScript printer, cgpdftops converts the color spaces in the
PDF into PostScript color spaces. In 10.2 this is the unconditional
behavior. For 10.3 there is a switch in the print dialog's ColorSync
panel that lets the user decide whether the color matching should take
place on the Mac or in the printer. If the color matching is done on
the Mac then the color spaces and colors drawn are flattended, color
matched, to a single space and that is set in the generated PostScript.
If 'In Printer' matching' is selected then the 10.3 behavior is the
same as 10.2.
Applications which Spool PICTwPS
The PICTwPS spool file captures RGB QuickDraw graphics and fragments of
a PostScript stream as specified by the application. The RGB drawing
can be tagged with RGB color profiles. The pictwpstops filter converts
the color spaces in the spool file to PostScript color spaces.
------- End of forwarded message -------
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