Patent ID: 8253783

Claim:
An electronic endoscope signal-processing device, comprising: a gradation compensation processor that compensates for R, G, and B gradations by controlling R, G, and B tone curves defining a relationship between input values and output values individually for R, G, and B signals; and the R tone curve shaped so as to squash the output value of the R signal when the input value of the R signal is in a low range and to expand the output value of the R signal when the input value of the R signal is in a high range relative to the low range, wherein the G tone curve is shaped so as to squash the output value of the G signal when the input value of the G signal is in a low range or in a high range, and to expand the output value of the G signal when the input value of the G signal is in a middle range, which is between the low and high ranges of the G signal, wherein the B tone curve is shaped so as to squash the output value of the B signal when the input value of the B signal is in a low range or in a high range, and to expand the output value of the G signal when the input value of the B signal is in a middle range, which is between the low and high ranges of the B signal, wherein at least the middle range of the B signal includes a range higher than the middle range of the G signal, or the middle range of the G signal includes a range lower than the middle range of the B signal, and wherein the high range of the R signal does not overlap with the middle ranges of the G and B signals.