Summary: How to get pure black shadows in RGB workflow
Summary: How to get pure black shadows in RGB workflow
- Subject: Summary: How to get pure black shadows in RGB workflow
- From: Miika Lammela <email@hidden>
- Date: Wed, 5 Jan 2005 15:01:12 +0200
Our customer is using InDesign CS/Mac and images are placed in the
layout in both CMYK-PSD and RGB-PSD format. In order to be able to
take full use of the advantages of RGB workflow, they would like to
place all images to InDesign in RGB color space.
They want to build mechanical shadows for many of the images (mostly
catalogue product shots), and they want to do that in Photoshop CS.
The images are then saved, with the shadow on its own layer, as PSD.
Optimally, the CMYK conversion should then be done later, either with
InDesign or even after the PDF has been created. When the shadow is
created in RGB, problem is, that the shadows get to be made out of
all four CMYK colors, when the ideal case would be pure K. The CMYK
numbers are of course depending on which press profile is used. But
even with a heavily acromatic profile, there's still a fair amount of
CMY. In the press that can cause the color of the shadow to shift
away from neutral.
Any suggestions on how to solve this issue??
I will now try to summarize the tips that you people kindly suggested
to solve the issue, together with my own thoughts and experiments.
Tip 1. "Use InDesign's own Drop Shadow feature... drop shadow is then made out
of K only."
My comment: This would be a good thing, if you could at least, rotate
and distort the shadow. If am not mistaken, you can only create a
simple drop shadow in InDesign, not modify it in the ways mentioned
above.
Tip 2. Create a spot channel to the RGB image for pure K.
My comment: Theoretically this could actually work, but unfortunately
InDesign does not seem to allow placing of such RGB-PSD that contains
a spot channel (at least in my testing it didn't).
Tip 3.
Don Hutcheson has made some strong arguments for 4/c drop shadows
rather than K-only :
-graybalance errors on press are less apparent (grays in image match
grays in shadow regardless of press drift)
-screening is the same between product and shadow (as opposed to a
rosette in the 4/c image next to a single channel shadow)
-press misregistration issues eliminated (white lines between k-only
shadow and product when registration drifts).
My Comment: This seems interesting. Has anyone more experience on
this, maybe some pros and cons, and what if we are talking different
types of separation profiles. I suppose if you use a UCR-profile with
black starting very late (say from 40%), you can get pretty big color
shifts in the shadow. Probably more useful with heavy GCR or MaxK
profiles?
Does anyone have experience of using a MaxK press profile for
sheet-fed or web offset printing with standardised conditions? I'm
thinking it might be a worthy way to get a "compromise solution" for
this RGB-workflow shadow issue, without any hassle or work-arounds.
Tip 4. "Create shadows in RGB and convert to a K-only profile... may
create a workflow issue in InDesign as the shadows need to be
converted to a different profile than the rest of the images."
My comment: I don't see this option usable, because the shadows would
actually then be separate image files and that gets far too
complicated. InDesign can not separate shadows in RGB image with a
different profile even if they are originally on a separate layer in
the PSD. That is because InDesign CS always uses a flattened version
of the PSD and if the file does not iclude a flat version (like it
does by default by Photoshop's "Maximize Compatibility" function) ID
will flatten the image before placing it.
I want to say thank you to all who have taken part in the discussion
of this topic. I will look forward to hearing your comments,
especially on the points regarding the use of 4-color shadows and
possibly MaxK press profiles (which I can produce with ProfileMaker
Pro 5).
Any other ideas?
Miika
--
PrePress Studio
Miika Lammela
Turunlinnantie 8
00930 Helsinki
FINLAND
+358-50-3737471
http://www.prepress-studio.fi -Training and consulting for graphic arts
and visual digital communications
http://www.prepress-center.fi -Dealer of computer, software and peripheral
solutions for graphic arts and visual digital communications
http://www.prepress-center.fi/icc -Solutions for icc color-management
and workflow color control
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