>>It might be what we have to do if we want to relinearise ourselves, but it's not what IJM does.<<
Not trying to argue this to death, but...
The "problem" that needs solving is how to get from a single master curve to a finished linearized curve with just one printed target. I am not saying exactly how they are doing it, but generally what the method and result is—establishing a limit/black point and adjusting the y values up and down (which is what causes the shape to change). It wasn't obvious to me either when looking at the master curve compared to the linearized ones, but it over the course of a few months staring at the ceiling it started to make more sense, and what led me to I prototype my custom QTR toolbox. It worked and was a nice challenge at the time, and then I moved onto other things. I just use it to keep a couple of wonky printers working with some custom ink mixes. This thread got me to fix up and change a few things on my original kit to make it more flexible for different printers and ink sets. When I get some more time I might make a post about it, but there are a bunch more in the pipe, and trying to wrap up other writing first...
Do you have a specro you can measure the QTR 21x4-random and/or 51-step targets printed with the k7 or k6 P2 master curve, and then email the measurement files to me? If not, then just send me an email through my site and I will send you a few screen shots illustrating what is happening here with some tests I did for someone today.
Richard Boutwell
richard @ richardboutwell.com or the contact form on www.bwmastery.com