QTR-Quadtone RIP

Hi Steve,

> I am trying to create a neutral curve for Epson Enhanced
> Matte paper. I am using Lyson Cave Paint pigmented Inks 
> on an Epson 7600 printer. 

> I started with the enhanced matte warm curve for the 7600 ...

Do the Cave paint inks generally print similarly to the UC inks?  If they are close, starting with a UC profile probably will work.  You could also just print the necessary 21-step test strips to do a fresh partitioning.  You might end up with a closer fit to the ink.  But you may not want to get into this yet.

 
> ... Here is a quote from the user guide:
> 
> "Once you print a step wedge, the next task is to visually assess the overall appearance of the print. Can you see all 21 distinct densities? Do they appear more-or-less evenly space. ..."

> Back to me. I can see the distinct densities in the highlights and mid tones, but when it gets to the shadows, they start bunching up and are too close to each other in density. ...

That is one of the reasons to start from scratch.  The curve you're starting with is probably not very well partitioned for the ink you're using.

But, it might still be fine.  

I actually prefer compressed shadow tones on pre-linearization curves, as long as there is some minimum separation so that QTR doesn't refuse to partition the input.  Many of the errors I see in final curves are due to the software not having enough deep shadow information.  If the information is not there QTR will interpolate.  In the deep shadows where the curves are in steep cross-overs the interpolation may miss the mark.  Actual information as to what is going on down there really helps the system.

I prefer to read the 21-step curves with a spectro and then graph the results.  This is a far more accurate what to "see" what is happening than just eye-balling it.  I use Excel to do the graphing.  There are other programs, and OpenOffice.org spreadsheets can do the job also, though more steps are needed.

At any rate, for eye-balling the deep shadows, if you can't see into them very well even with a good light, put a strong light behind the print.  Reflective light passes through the ink twice -- transmissive only once.  So, the effective density is cut in half and it's much easier to see what is going on in the deep shadows.

Good luck.

Paul
www.PaulRoark.com