The digital color instrument (PHOSDAC-1000 made by Kimoto K.K.) divides density values of photographs into 12 steps colors, and calculates percentage of those each occupation rate.
This paper offers the data of examination results about this performance of this instrument, and points out some good efficiencies and some faults of this instrument.
I should say that dividing is good but that the error of planimation is not negligible.
