[Gs-devel] ICCBased color spaces with color ranges other than [0..1]?
L. Peter Deutsch
ghost at aladdin.com
Mon Oct 22 08:41:18 PDT 2001
I've almost finished upgrading pdfwrite to convert general CIEBased to
ICCBased spaces (since PDF has the latter but not the former), but I have
one remaining problem: I can't figure out how to get the input range of an
ICCBased space to be other than [0..1]. This is a problem, because CIEBased
spaces can have arbitrary ranges. For the color in the graphics state,
pdfwrite can do the normalization step itself; for colors in images, I think
adjusting Decode can always handle it; but I don't see how to make either of
these approaches work for shadings. I'd really like to hear from someone
who actually understands the ICC profile spec as opposed to just having
floundered through its text, which is really awful (incomplete, vague, very
poorly organized, ...).
To confuse matters further, the Adobe documentation (PDF Reference) says
that ICCBased spaces include a range specification that "must match the
information in the ICC profile", and that the PDF spec is based on "version
3.3" of the ICC profile spec. However, ICC's version numbering seems
broken: "version 3.3" of the spec, dated November 11, 1996, corresponds to a
file version number of 2.1.0, while the document describing file version
2.2.0 is identified as "ICC.1:1998-09", with a 1998 copyright, and an annex
"ICC.1A:1999-4" copyright 1999.
Any enlightenment would be greatly appreciated. TIA.
L. Peter Deutsch | Aladdin Enterprises | 203 Santa Margarita Ave.
ghost at aladdin.com | http://www.aladdin.com | Menlo Park, CA 94025
The future of software is at http://www.opensource.org
More information about the gs-devel