Re: What rendering intent for RGB to CMYK
Re: What rendering intent for RGB to CMYK
- Subject: Re: What rendering intent for RGB to CMYK
- From: Henrik Holmegaard <email@hidden>
- Date: Thu, 7 Feb 2002 08:52:08 +0100
email@hidden (Bruce Fraser) wrote:
Paper White and
Ink Black are display-only controls, quite separate from the
transform from source to simulated proof space.
The UI of the Proof Setup window is poorly designed, like so -
a. the Simulation checkboxes refer to the Source - Simulation -
Destination monitor transform,
b. the Profile popup refers to the Source space for which the default
is set in Color Settings,
c. the Intent popup does ditto except there is no indication of the
status for Use Black Point Compensation,
Thus the Profile and Intent popups affect both the Source -
Simulation - Destination monitor soft proof and the Source -
Simulation - Destination proof print transforms.
Thus the source space for the soft proof and proof print is defined
in Proof Setup and not in Color Settings. This also holds true for
the intent for the Source to Simulation transform, except it doesn't
wash because there is no way to tell the BPC status from the Proof
Setup window. That takes a visit to Color Settings.
Thus the source space but not the BPC setting is shown in the Pshop
PS driver dialog. That takes a visit to Color Settings, too.
IOW BPC has poorly implemented UI.
where the production stock is exceedingly
similar to the proofing stock, I'd use RelCol. I'd probably also turn
off BPC, though I suspect that in this scenario it would make very
little difference...
Any printing system has a first printing point. If the paper white of
the simulation space is only slightly above that of the destination
space, the first printing point will be higher than what is to be
marked on the paper.
Caveat: If the simulation space is characterized using black backing,
then the white point will be a couple of steps lower than if it were
characterized using white backing (this problem also occurs with some
spectrophotometers when measuring with white backing). The choice of
backing for characterizing the simulation space will thus affect the
definition of the paper white, often lowering it into the range where
the first printing point causes the proofer to mark the paper. Either
characterize both simulation space and destination (proof) space
using black backing or using white backing, but preferably not a mix
of the two. FOGRA points out that characterizing with black backing
allows the use of black backing when using a spot spectro to verify
color reproduction on the final printed sheets (: so colors on the
other side of the sheet are factored out as much as possible). On the
whole it seems to me that white backing is preferable ... as offset
papers become better why compress the lightness range a couple of
steps?
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