Rendering intents in source profiles?
Rendering intents in source profiles?
- Subject: Rendering intents in source profiles?
- From: Uli Zappe <email@hidden>
- Date: Wed, 23 Jul 2008 17:31:23 +0200
Hi everybody,
while working on the scanner profiling part of the Mac Life color
management review (I'll report the results when the new article will
be published), I wondered what rendering intents actually mean for
source profiles, i.e. for profiles whose A2Bn tags are used.
For instance, take the classic example of a conversion from working
space to printer space. Since the printer space is smaller, gamut
compression or clipping obviously has to be performed. *But* this
should take place in the B2An tag of the printer profile (= target
profile), which "knows" about the limitations of the printer and can
adjust the gamut accordingly. I don't see which role the working space
profile (= source profile) could actually play in its A2Bn tag, since
the PCS will by definition be able to represent all colors, so
whatever colors the working space comprises, there will be no need to
perform gamut compression or clipping when converting colors from the
working space to the PCS (which is what the A2Bn tag does).
So why are there rendering intents for A2Bn tags, and what do they
actually do? The ICC spec does define separate perceptual,
colorimetric and saturation intents for A2Bn tags (A2B0, A2B1 and
A2B2), and if you test real world profiles as built by e.g.
ProfileMaker, you will find that they do produce different PCS Lab
values for the three intents. But according to which logic??
Thanks a lot in advance for any insight!
Bye
Uli
________________________________________________________
Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
http://www.ritual.org
Fon: +49-700-ULIZAPPE
Fax: +49-700-ZAPPEFAX
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