QTR-Quadtone RIP

--- In QuadtoneRIP@yahoogroups.com, Michael King <drmrking@...> wrote:
>
> Of course I should have said how you get from L* 0 - 10 in your on screen
> image ...
> Robert shadows are low L* values. I am not 100% sure what you mean by "matte
> papers in the deep shadows (90-100)"
> What does the 90-100 refer to ?
> 
> Mike
> 
> 2009/8/1 Michael King <drmrking@...>
> 
> > Robert,
> >
> > Here are the L* readings I measured some time ago with HPR+K7 on the R1900
> > for RGB 0 - 27
> > It turned out it wasn't a particularily good batch of HPR I chose to
> > measure with 256 steps.
> > often I can get down to L* 16.x
> >
> >     RGB, L* 0 17.75519 3 18.5508 6 19.38313 9 20.26813 12 21.233 15
> > 22.31181 18 23.18398 21 23.84067 24 24.91842 27 25.61255
> >
> > So as you can see K7 puts out good seperation between low RBG values. In
> > fact its pretty much linear across RGB 0 - 255 range. How you get from L* 90
> > - 100 in your on screen image to something on your printer that shows
> > seperation in those values is a workflow/profiling issue not a K7 issue.

Thanks, Mike.  I should have been more specific (end of a long day:)  I was refering to the 90-100 steps of a 100 step grayscale.  I can see from your readouts that the Piezography profiles/inksets are getting something I cannot duplicate with QTR and a custom inkset I'm playing with.    The inkset is Eboni Matte Black and 6 dilutions of HP Vivera Black plus glop.  The obvious goal is a dedicated b&w 8 head printer with matte and glossy capabilities.  (I've been patiently waiting for J. Cone to do all the work:)  Piezography seems to be going in another direction so I decided to play with it myself.  

The hang up on this and a previous UT-3D inkset with the 1800 has been separation in the deepest shadows and artifacts at the transition to the MK ink.  When looking at Cone's .quad files he obviously has a different method of profiling (creating the curve files) for QTR.  One obvious aspect is that he is able to overlay his individual ink curves in a way that QTR, in it's native partitioning, does not.   Everything in QTR seems to be contained in the .quad file instructions to the printer, but, how you get there seems a matter of choice.

I'm happy to note that you are using a 1900.  I think it's close enough to an 1800 to eliminate the printer as the source of the artifacts, or at least there IS a method of profiling that printer that can eliminate them.

Robert