QTR-Quadtone RIP

Ken,

If you are looking at the info palette it is probable that the shadows are
not compressed, though they appear to be. This relates to the fact the same
density is represented by different K% in different grayscale gamma spaces. 

I created a grayscale step wedge in gray gamma 1.8, made a copy of it, and
then converted (not assigned) the copy to gray gamma 2.2 using Edit/Convert
to Profile. When I measure the same patch on the two different step wedges I
see that the K% is different. 

The issue is whether the different values of K represent different densities
of gray. I think they do not. 

In my example, when I measured the same grayscale patch in the two different
grayscale wedges, I get 96% K in the gamma 1.8 space and 92% K in the gamma
2.2 space. These actually represent the same density. 96%K in a 1.8 gamma
space is the same level of gray as 92% K in a 1.8 gamma space. (See the
"Companding Calculator" calculator on this great website:
http://brucelindbloom.com)

Though it is not too intuitive, an analogy is that PC monitors calibrated to
gamma 2.2 monitor have a darker display for the same RGB values sent to Mac
gamma 1.8 monitor. Since gamma 2.2 displays darker, 92% black on a gamma 2.2
monitor would be the same level of gray as 96% gray on a gamma 1.8 monitor. 

Seeing compressed shadows on actual prints is a different issue. If you are
actually converting between gray spaces instead of assigning the gray
spaces, it seems like the prints should not have different shadows. 

Steve Bye

-----Original Message-----
From: QuadtoneRIP@yahoogroups.com [mailto:QuadtoneRIP@yahoogroups.com] On
Behalf Of prof_mgt551
Sent: Saturday, June 03, 2006 7:03 AM
To: QuadtoneRIP@yahoogroups.com
Subject: [QuadtoneRIP] Re: Roy's working space blocks up shadow detail? Why
use it?

Hi Duane,

Thanks for sharing your experience with this issue. The only gray 1.8
that I have is gray gamma 1.8. When I convert to it from the gray
gamma 2.2 space, the shadows are also compressed (using the info
window in Photoshop to check the K % value). I am do not understand
why the deep shadow steps are compressed when converting to these
other spaces?

I can see deepest shadow detail on my screen but I loose it in the
print unless I use the gamma slider to open up the tone curve. I would
prefer not to do this, since I assume the response is no longer
linear? I tried the gray matte paper profile and others for soft
proofing and didn't see any change.

I think the basic problem is there is no software that allows you to
softproof the QTR Printer output. Roy mentions this in his ICC
Info.txt file, " The current version creates profiles for the printing
side.  A soft-proofing version is coming soon."

Best wishes,

Ken