QTR-Quadtone RIP

##Linearizing

Sandy basically covered it. The only point I would like to clarify is that Density from a densitometer can be used to arrive the Lab values QTR needs in the LINEARIZE= line. The Linearize-Data app will actually do a Density to XYZ\_Y to LAB\_L to produce the Linearize="" string. I have never tried just entering Density values into the Linearize= line. Roy might need to correct me, but I THINK there is something in the curve creation script that will check to see if the values there are L\* or Density, and if it is Density, it will convert it to L\*


If you want to make your own Lab to Density and back conversion there is a formula to do that can be found a few different places online. This is one of my favorite posts someone had written on the subject: http://stonerosephotos.com/blog/2012/01/ink-density-reflectance-and-l/

I made this tool that does these conversions a while back: https://www.dropbox.com/s/nrcxze38fmbruiu/BWMASTERY%20Lab%20to%20Density%20Conversion%20Tool.xlsx?dl=0

You can't use Density without translating to L\* for the QTR Linearization because Density is a logarithmic scale, and linearizing to create evenly spaced Density patches will end up with a print that appears too dark compared to what QTR does with linear Lab L\*. It actually can be done if you are using the gray curve line but will mean that you can't use Linearize line (it will recorrect the linear Density to linear L\*

I actually made a version of my gray curve correction tool for digital negatives for someone last year who wanted to create linear Density rather than linear L\*. He was attempting to compensate for the lower dmax and overal lower density of the PTPD print compared to what a normal inkjet print was producing and what he was seing on the screen. It worked to some degree, but was't compatible with all the other stuff out there so I never posted more about it. It was just another option/take on the linear/compressed shadow issue when dealing with processes with a lower Dmax.

This has gotten pretty far off the original subject but I did say it was hard to talk in gerneal terms about Linearization with a text file...

Richard Boutwell