Re: Of black point compensation (short version -:))
Re: Of black point compensation (short version -:))
- Subject: Re: Of black point compensation (short version -:))
- From: Henrik Holmegaard <email@hidden>
- Date: Sat, 7 Jul 2001 20:29:16 +0200
Lasse Seppala wrote:
So if I ask PS6 to show me how a separation of RGB_xx would look
like in >Press_yy, I go to View/ProofSetup/Custom and take the
Press_yy-profile.
No, that has to be wrapped in a clause or two.
By default the profile shown in the Proof Setup > Custom window is
the 'Working CMYK' profile set in Color Settings.
You can use the Profile popup in the Proof Setup > Custom window to
choose another CMYK space, or an RGB space, for instance.
With the intent I select how the resulting separation would look
like as >separated with relative or perceptual intent
Again this is an override for the intent from source to simulation
chosen in Color Settings, so you're right.
(I suppose this is not affecting cie/monitor, which should be
relative on top >of everything). With Paper white (and black
checked) you have >absolute-cmyk-simulation (with BPC) on your
monitor. With only Black ink >checked you get
relative-cmyk-simulation with BPC on monitor.
Simulation space to destination space (monitor space) is governed by
these three controls:
a. Proof Colors (Relative Colorimetric with relative black point to
the deepest black of the monitor = RelCol with BPC)
b. Simulate Ink Black (Relative Colorimetric with absolute black to
keep the monitor blacks as light as the real printed blacks - same as
Linocolor / Newcolor without checking 'Media white point simulation')
c. Simulate Paper White (Absolute Colorimetric with absolute white
and absolute black matched froun simulation offset/gravure/newsprint
space to destination monitor space)
You must have set perceptual/actual
press pofile in color settings for this kind of softproofing to work
correctly. If it is set relative in Color settings, screen proofs
are identical >(relative) with both intents in proof settings.
Nope.
What you do in the step from source RGB / Lab space to simulation
offset CMYK space is independent of what you do in the simulation
offset CMYK space to destination monitor RGB space.
If the monitor soft proof transform works correctly in an
application, it will simply show you what you did in the source to
simulation transform. If there are catastrophes, it'll show them, too
-:).
It is also best bet to have it perceptual (as discussed earlier) to
get safer >separations by somebody pressing CMYK-tab without
checking first what is >happening.
Yes.
The best way to separate is always to use convert-to-profile -dialog
(you can >check surely the settings) and to have BPC on (unless you
want deeeeep shadows >beyond the paper facilities) if you use
relative conversion.
In the Pshop 5 and 6 UI, BPC explicitly refers to the source to
simulation transform. In this transform you can't make the shadows
deeper than they really are (but you can clip the shadow detail).
However, without using the same word BPC is also applied in the
simulation to destination monitor RGB transform which in Adobe
applications by default is Relative Colorimetric with relative black
point which is the same as BPC except it's called 'CMYK Preview' in
older versions of Pshop and now 'Proof Colors'. But it's not a
relative colorimetric transform in the ICC sense (with a risk of
invoking the wrath of the Gods for this one -:)). I'd need to hunt
for the revised spec to figure out what's afoot now, but I'd guess
it's written in at this time.
I'm sorry if you find all this confusing, and it is, too -:).
Hmm ... maybe I should read the post again ... I'll risk it, the
coffee will get cold ...