Re: Linocolor and Printopen rendering problems
Re: Linocolor and Printopen rendering problems
- Subject: Re: Linocolor and Printopen rendering problems
- From: Henrik Holmegaard <email@hidden>
- Date: Sat, 7 Jul 2001 12:49:26 +0200
Kellie Kulton, Whipped Cream at AOL dot COM, wrote :
We created a grey scale in Photoshop which was pure grey throughout
the scale. >When opened in Linocolor it was no longer reading even
amounts of RG&B.
The idea is that you create a device independent grayscale (L 0 a 0 b
0, L 5 a 0 b 0, L 10 a 0 b 0 ...) which applications should show the
same. If you create a device dependent grayscale, then you need the
same profile to get the same behaviour. Launch LinoColor 6.0.10, go
to File > Profile Setup > Open / Save, and in the Gray panel choose
set a default grayscale profile.
If we convert using perceptual rendering, which is what we do use,
LinoColor 6.0.10 uses Perceptual B2A0 from Lab to CMYK and
Colorimetric A2B1 (+/- white point simulation) from CMYK to Lab in
the printer profile. This means that your soft proof is always based
on a perceptual rendering going into the CMYK destination space, and
always based on a rendering to the monitor that behaves the same as
Pshop 6 with the Ink Black setting.
(NB the Ink Black setting is so far as I can determine broken in
Adobe software other than Pshop 6 which will neither match Pshop
6.0.2 with Ink Black nor LinoColor 6.0.10 with 'Proof with media
white point simulation' that sets an absolute black point match from
offset space to monitor space.)
the color change is perfect but the picture lightens noticeably
As I have no way of seeing what image and what offset or gravure
space the behaviour refers to, I'm fumbling here.
In general the danger in reproduction is always in the shadows.
Scanner folks tell photographers to open up their shadows or the
stuff won't print. Photographers look for deep shadows to get pop and
contrast. It's one of these evergreen issues.
First of all set the two applications to work the same way. When you
set Pshop 6 to Perceptual in Color Settings (this is the B2A
direction from Lab into CMYK in the printer profile), and to Ink
Black in the Proof Setup window (this is the A2B direction from CMYK
to Lab in the printer profile), and in LinoColor 6 .0.10 disable the
Simulate media white point checkbox, you have a basis for direct
comparison.
Now if you are matching perceptually, the people who built the
perceptual look-up table will try to help you avoid problems. They
tend to have a reasonably educated idea of what will print well and
what will not print well -:). Using the perceptual look-up table the
printer profile will try to open up the shadows while at the same
time maintaining the color contrasts.
But if you switch Pshop 6 to Relative Colorimetric, all L steps from
your deepest RGB working space black to the deepest black of your
print space will map to the deepest black of the print space because
the blacks map absolutely. And if you switch Pshop 6 to Relative
Colorimetric with black point compensation, you will get more like a
linear black that does not chop your shadows, but also does not
favour them with a soft hand -:).
I'd think you'll find the behaviour similar once you set up the
applications the same.