Thanks for the info.(posted 8162 days ago)The reason I wanted such a strange pairs of density steps was because I wanted to make sure that the measurement system works to my expectation, not too much of practical requirement. Also, the density of the base itself doesn't concern me as long as it's small and uniform. My scanner gives me 16 bit data for each channel up to density of 3.5 or so. This leads to a statistical model estimation and verification problem. Once I get that part done, I can just use the model. You don't want to use the model that you don't know how good/bad it is.