QTR-Quadtone RIP

Steve and Steve,
   I have been happily  making curves for my Epson PS1400 and the MIS UT-14 inkset.  Some of my curves definitely are "bumpy", but the output seemed OK.  But, after reading your posts, I downloaded the test file from Northlight and saw distinct rings in the radial patterns when I printed them.  As you describe, the discontinuities in the output correspond to the places that the curves look bumpy.  I played around a bit with smoothing the curves, and was able to improve the output significantly.

This seems to me to be a weakness in the QTR curve-generating programs, especially when the "linearization" routine.   My suspicion is that the problems are worst when the curves have to be modified extensively to linearize them.  It might be that the problem can be minimized by better optimizing the original curve, through judicious choice of parameters, so that the linearization routine doesn't have to distort the curves so much.


Has anyone asked Roy Harrington about this problem? 


David