Re: Custom ICC Profiles/Conversion Rending Intents
Re: Custom ICC Profiles/Conversion Rending Intents
- Subject: Re: Custom ICC Profiles/Conversion Rending Intents
- From: "Harold Boll" <email@hidden>
- Date: Mon, 20 Jun 2005 07:33:14 -0700
- Thread-topic: Re: Custom ICC Profiles/Conversion Rending Intents
Chris Murphy writes on Sun, 19 Jun 2005 09:36:35
> They're absolutely related. So long as CMY alone won't
> produce as dark and neutral a color as 100K, some black
> generation is necessary, even at a 400% ink limit. But
> as ink limit decreases, by definition black generation
> increases, and vice versa. .............
> There really is no such thing as light GCR for a 240%
> ink limit, .............
In my view Total Area Coverage (TAC, a.k.a. 'ink limit') and GCR are
independent Profile parameters. The Black Point of a profile (darkest
color which may or may not be neutral) is determined by 2 parameters:
Black limit and TAC - its inking is achieved by starting with that %K
limit and adding CMY until TAC is reached. GCR has nothing to do with
its determination. Black generation on the neutral axis is determined
by 2 additional parameters: BlackStart (point at which K commences) and
GCR (shape of K curve connecting start and endpoints). So, in essence,
GCR determines the shape of the K-curve connecting the Black Start Point
and the Black Point - it doesn't determine either of those 2 points.
One aspect of Profile generation where there may be a linkage is in the
extent of the gamut being built in the shadow region. Some profile
packages may choose to link the size of the gamut to the GCR setting;
higher GCR implies more K which implies a greater gamut is swept out in
the shadows. This would be a choice on the part of any Profile
Generation package - it is entirely possible to build the largest gamut
possible which is independent of GCR as well.
Harold
Creo, a Kodak subsidiary
3 Federal St., Billerica, MA 01821
IMAGINE CREATE BELIEVE "The sunlights differ, but there is only one
darkness." Ursula K. Leguin
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