QTR-Quadtone RIP

The whole "I need an ink level of 60% to produce the correct tone at the 50% patch is a very general way of looking at it". The spreadsheet I linked to does all that for you much more precisely by creating the linear target values and then doing an interpolation for each of the points between the Dmin and Dmax. This is the same kind of interpolation mentioned in one of the calibration PDFs for doing a proper cross over point calculation. But instead of needing to do 60+ different measurements and 19 interpolations you just need to enter the density readings—either manually or by copy and pasting—and the template does the rest for you.