Thanks for your detailed explanation. That is essentially what I though the answer had to be, I just couldn't figure out how to go about doing it (my own damn limited skills with the maths)
I'd love to talk more with you about this by email when you have more time. I've spent the better part of a year creating, refining, and using excel templates to average multiple readings to get exact cross-over and linearization values for making 6-gray channel QTR profiles that come close to the long-tailed curves that Jon makes. Although the his curves make much smoother gradients, if you can average out the measurement variances, the qtr ones come really really close. The issue with the QTR curves is the shape for each channel changes abruptly at the top end so any mistakes are in the ink limits or cross-overs point make obvious bands on smooth gradients.
Anyway, I will work on getting the i1 profiler stuff sorted and get back to you.
Richard Boutwell