QTR-Quadtone RIP

Tom,

The compression in the two steps is interesting. Also, I think you are
right, printer variation probably accounts for different output
results. I assume that QTR curves are specific to a particular printer
just as ICC printer space profiles are specific to a particular printer.

I had a client that wanted B&W prints so I went ahead and converted
the files to my Ilford Smooth Pearl ICC profile and used your Ilford
Smooth Pearl curves in QTR. It was important that the client got a
close screen match with the prints, so I adjusted the gamma slider in
QTR to a -7, which gave a better screen match. We were pleased with
the results. The prints looked very close to silver emulsion prints.
But I think they could still be better. 

I feel that I may be loosing some image quality by having to use the
gamma slider in QTR. But maybe my screen, even though its calibrated,
is the reason I don't get a close screen to print match? QTR and B&W
digital printing is new for me. I feel comfortable with color and
creating color ICC profiles, but I don't feel that I have a handle on
QTR and curves. When I get a chance I may go ahead and try using a 51
step gray scale to re-linearize the curves.

Kodak sent me samples of their professional lustre inkjet paper. I
printed a test using the same ICC space and curves that I used for the
Ilford Smooth Pearl. The results were close to the Ilford paper. The
Kodak paper is slightly whiter but not quite as heavy as the Ilford
Smooth Pearl. DMax was close.

Best wishes,

Ken

 
--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <r.t.moore@...> wrote:
>
> Ken
> 
> I checked out the gray gamma 2.2 test image. It is interesting (to me
> anyway) that after Converting to Qtr-gray-photo paper profile the
95% step
> is actually 98%k and the 90% step is 95%k. So the conversion process is
> definitely compressing the shadows. However, when I created the curve, I
> used the 21 step image (over a year ago now, so my memory is vague).
That
> means that the process did not empirically verify any linearity
between 95%
> and 100%. One might assume that the curve would be linear between
measured
> steps, but that assumption gets riskier as the steps get larger. Your
> suggestion to try the 51 step test image might be the answer.
> 
> The QTR-Create-ICC utility will work with 51 or almost any number of
steps.
> 
> Another point I forgot to mention in my first response is that there
may be
> printer variations at play here. In looking at my notes from the
creation of
> the ISP curve, the dmax I achieved was around 2.17. Your measured
dmax is
> around 2.22. Given, as you state, the effect you seeing is subtle,
this may
> also be a factor. 
> 
> If you do decide to re-linearize the curves or create an ICC using
the 51
> step file it would be useful for others to update the curves I
posted. If
> you provide them to me I'll do that.
> 
> Tom Moore
> 
> > -----Original Message-----
> > From: QuadtoneRIP@yahoogroups.com
[mailto:QuadtoneRIP@yahoogroups.com] On
> > Behalf Of prof_mgt551
> > Sent: Friday, May 26, 2006 9:07 AM
> > To: QuadtoneRIP@yahoogroups.com
> 
> 
> ...
> 
> > Perhaps there is something wrong in my procedure. My display is
> > calibrated and profiled. Maybe I should use the 51 step scale. I
> > wonder if the QTR-Create-ICC tool will work with 51 steps. The sample
> > files are set up with 21 steps.
> > 
> > Appreciate any thoughts you or other forum members might have. Thanks
> > for making the Ilford Pearl curve available.
> > 
> > Ken
> 
> ...
>