QTR-Quadtone RIP

Joost: 

In general I also use your WF1.  But I edit with Pictrue Windows Pro 
using the softproofing QTR RGB icc profiles I generated from 
linearized QTRgui printouts of the QTR 21step wedges and a similiar 
rendering intent as you.  

1) In my case editing starts with 16-bit RGB images (usually in 
AdobeRGB) that I first convert to 16-bit BW using the Picture Windows 
equivalent of a channel mixer.  Conversion removes any profile tags.  
[Note the softproofing monitor image of the RGB image is BW.] 
2) Set B/W points and use curves (combinations of RGB, HSL, and HSV) 
to get the 16-bit on screen image I want.  
3) Resize for printing.
4) Sharpen as needed.
5) Use Neat Image to remove grain as needed.
6) Save the image as a 8-bit tiff image.
7) Print through QTRgui using the .Quad profile used to create the 
softproofing icc profile.  

Unlike your Step 4, I don't tag or convert my images to any profiles 
during my workflow--QTRgui seems to work just fine.

Jeff


--- In QuadtoneRIP@yahoogroups.com, "Joost Horsten" <j.h.j.h@...> 
wrote:
>
> 
> Hi all,
> 
> In view of the confusion we had lately on this forum on the 
different
> QTR workflows, I decided to do a small experiment, comparing two
> workflows.
> 
> Workflow 1
> 1) editing the image. I used both AdobeRGB and Gray Lab as 
workspaces,
> without differences, and (at least to my understanding) the editing
> workspace is of NO relevance here. Any workspace will do
> 
> 2) softproofing the image with the gray-matte-paper icc profile
> (setting: "preserve numbers"=OFF, "rendering intent"="relative
> colorimatric", "blank point compensation"=ON, "simulate black 
ink"=ON)
> 
> 3) flatten, convert to 8-bit grayscale
> 
> 4) convert profile to "gray-lab" and save as tif
> 
> 5) print the image with QTRGUI
> 
> Workflow 2
> 1) editing:  same as workflow 1
> 
> 2) NO softproofing
> 
> 3) flatten, convert to 8-bit grayscale, smae as workflow 1
> 
> 4) convert profile to "gray-matte-paper" and save as tif
> 
> 5) print the image with QTRGUI, same as workflow 1
> 
> 
> The hypothesis for this experiment was that these workflows, 
although
> different, are actually equivalent.
> 
>   It's hard to get the hard physical, quantitative evidence from the
> results.  It would involve direct comparison of screen luminances 
with
> print luminances and  I do have a spectrometer but I have currently 
no
> idea how to directly compare emissive and reflective values.
> 
> Nevertheless a qualitative comparison DOES support the hypothesis. 
In WF
> 1, the softproofing lightens  the image, with respect to the 
original
> image. So if ones edits with Softproofing "on", the actual image is 
a
> bit darker. In WF2, the conversion of the image the gray-matte-
paper,
> darkens the image. This is NOT visible on the screen, since 
photoshop
> compensates for this, but it can be checked with the eye-dropper: 
the
> LAB values drop (or the K-values increase which is the same) after
> conversion.
> 
> So in BOTH cases  a darker image is sent to the printer than the one
> displayed on the screen.  My explanation is as follows:  the dynamic
> range/contrast of paper is lower than that of a screen. Paper can
> typically display L-values between 15 and 95.  So, especially in the
> blacks there is quite some descrepancy between paper black and image
> black.  Both WF1 and WF2 are ways to compensate for this. WF1 uses 
the
> gray-matte-profile to compensate the screen-paper difference on the
> screen, while WF2 compensates it in the printer.
> 
> WF2 is the workflow as advocated by Roy, WF1 is the one I (and some
> others) use. But now my (preliminary, since based on incomplete
> evidence) conclusion is that they lead to the same result. I 
personally
> always could live better with the theoretical foundation of  WF1, 
but
> now I think I understand that it's just a matter of taste.
> 
> Open for any comment and critique. For the ones more knowledgeable 
than
> I: please check if I used the right settings for softproofing.
> 
> Joost
> 
> 
> 
> 
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>