Re: Kodak 9500 resolved
Re: Kodak 9500 resolved
- Subject: Re: Kodak 9500 resolved
- From: Steve Upton <email@hidden>
- Date: Fri, 29 Dec 2000 11:04:08 -0800
At 7:20 AM -0500 12/28/00, Glenn Kowalski wrote:
Creating a device link profile with ColorThink using the Apple CMM
yeilded an 8 mb file which seemed to be damaged, so I used the
Heidleberg CMM which produced an 800k file.
I'm glad you were able to sort this out. I have not had time to
contact Kodak about the apparent inability to generate link profiles.
Anyone listening?
Then the device link worked and the output matched the relative
colorimetric intent I was going for. It seems the Harlequnn RIP
works fine with device link profiles, but doesn't handle standard
ICC profiles correctly.
The transformation used to proof may not be setup correctly. You
should contact Harlequin (or the appropriate OEM) to see if that can
be changed. This is a good example of the use of device link
profiles. You can create a device link you like on the system you
trust your color (Mac) and then the RIP just does the work instead of
having to be color smart.
One oddity though--I created the device link with the relative
colorimetric intent, but both the Harlequinn RIP and ColorThink
report it as Perceptual.
also...
At 11:41 AM -0500 12/28/00, email@hidden wrote:
I believe all device link profiles will state the Perceptual intent, no
matter what they actually use, due to a rather fuzzy piece of logic about
what profile's intent is involved.
At 12:05 PM +0100 12/29/00, Henrik Holmegaard wrote:
According to the spec the LUT is always named AtoB0 (: alphanumeric
naming scheme).
The actual intent is intended to be stated in the profile header
(Perceptual, Relative Colorimetric, Absolute Colorimetric,
Saturation: alphabetic naming scheme).
ColorThink just writes the alphabetic name tag wrong (: as
Perceptual when it's actually something else you've built).
I should clarify this a little to avoid confusion.
There is only one look up table (LUT) in a device link profile. There
are typically up to 6 in a normal printer profile.
When a link profile is created, the appropriated rendering intents
from the two "parent" profiles are chosen and melded into one table.
That table is labeled, in the structure of the profile, as "A2B0". In
a "normal" printer profile, the tag labeled "A2B0" refers to the
"device color->PCS" (eg CMYK->Lab) perceptual table.
So ColorThink and other device link profile generators are not
creating the profiles incorrectly, all of the above stuff is
according to the ICC spec.
The confusion arises in two areas:
1) ColorThink's Profile Inspector lists a description of each tag
type. So instead of trying to remember what the "B2A1" tag is
supposed to be doing, ColorThink describes it as the "Lab->CMYK
Colorimetric LUT" and you can understand it as the colorimetric
rendering table(for CMYK profiles of course). There is a UI oversight
(OK a bug) in the current release of ColorThink that incorrectly
describes the "A2B0" in a _device link profile_ as perceptual. It
should really (and does in the dot-release version to be released
soon) describe the tag as a "device->device lookup table" (CMYK->CMYK
lookup table for most proofing situations).
There is no way to determine, based on the contents of a
ICC-compliant device link profile the rendering intents used when the
profile was created. which brings us to..
2)
At 12:05 PM +0100 12/29/00, Henrik Holmegaard wrote:
The actual intent is intended to be stated in the profile header
(Perceptual, Relative Colorimetric, Absolute Colorimetric,
Saturation: alphabetic naming scheme).
I must disagree with my esteemed Danish colleague here. The header
tag for default rendering intent is intended to tell the system which
rendering intent to use when the user or the application has not
specified it. As the device link profile does not contain a list of
available intents, a preferred intent is moot. I suppose we could use
the preferred intent tag as a means to mark the profile with a
reminder of how the device link was created but I think there
probably better ways of doing this.
Best of the season to all,
Steve Upton
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