QTR-Quadtone RIP

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

...