Re: scanback profiling question
Re: scanback profiling question
- Subject: Re: scanback profiling question
- From: tom vanderlinden <email@hidden>
- Date: Thu, 8 May 2003 02:26:58 -0400
good morning - - -
So, if
the input>PCS part of the conversion gets built
using the specified rendering intent
and the PCS> target uses the default intent of the target profile,
it appears that for each initial choice of rendering intent
the following permutations exist:
Ask for Perceptual (for example), and you get:
input>PCS rendered Perceptual & PCS>working space rendered RelativeCol
*unless* target profile is not matrix based, then you could get:
PCS>working space Perceptual, or AbsoluteCol, or RelativeCol, or
Saturation,
depending on the default intent of the target profile.
So, I'm seeing 4 different permutations there,
multiplied by the 4 rendering intents
(and ignoring Black Point Compensation for the moment)
= 20 possible flavors to anticipate.
Someone please tell me I am wrong.
- - - Tom Vanderlinden
printing for preservation
On Saturday, May 3, 2003, at 01:44 PM, Roger Breton wrote:
Bruce Fraser said
If you have a LUT-based input profile, the input>PCS part of the
conversion gets built using the specified rendering intent. The
PCS>working space part of the conversion uses relcol unless the user
requests abscol, because the working space profiles are matrix
profiles, and matrix profiles contain only one rendering intent. In
theory, you can build matrix profiles using any rendering intent, but
the Photoshop WS profiles are all relcol.
I have been chewing on this for a week,
this is what I'm trying to swallow:
It sounds like we are saying that ONE
profiles and CMM-based conversion actually makes TWO
applications of rendering intent:
one from source to PCS, and
one from PCS to target.
True?
That is also my understanding. One the one hand, the Source profile is
invoked to convert the Device data to PCS (Lab) and then the
Destination
profile is onvoked to convert the PCS data to Device. It so happens
that on
either the Mac or Windows, the two Source and Destination profile are
"concatenated" into what is known as a "Gworld, the conceptual
equivalent of
a Device Link profile. At which time, you can imagine that the
conversions
are done at the speed of, well, silicium.
- - - Tom Vanderlinden
printing for preservation
Regards,
Roger Breton
Laval, Canada
email@hidden
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