The output with calibration mode is strictly 1 to 1 and there is no "curve" or any other behind the scenes adjustment to the file as it is sent to the printer. The point of the calibration mode is to see what the native linear response of the printer is so you can then correct for it in the profile creation process. The red channel determines what ink channel to fire, and the green channel determines the percentage of ink to fire—G-255 is no ink G-0 is 100% ink. The ink limit setting in the print dialog box controls how much is fired at the G-0 value, and all the values from G-255 to G-0 are linear relative to that overall ink limit. If you wanted to use a lot of paper setting your ink limits you could make a 256-step target for each channel and see exactly where the d-max for each shade is and where overlaps fall—overkill, even for me.
Higher end rips like Studio Print will actually linearize each channel individually. That isn't an option with QTR, but if you don't go crazy setting ink limits past where the dot gain curve levels off the native density increase is pretty much linear (at least for the lighter shades). The darker shades are controlled in some of the .qdif/.txt file options like ' GRAY_SHADOW=" " ' and ' GRAY_CURVE=" " '
New User Guide: I announced over the summer that am working on one. It was going to just be a short PDF, but as I get into some of the more advanced methods for making multi-gray profiles it is getting longer and needs a full ebook to cover the three different approaches for OEM and Thrid party gray inksets. My day job had me busy for the last few months and I haven't worked it all out yet. I am spending the next month hammering away on it, and should be ready early next year. The full book will also come with new targets, references files and methods for current software and excel templates for making the profile creation process easier.
Richard Boutwell
www.bwmastery.com
www.RichardBoutwell.com