Patent ID: 8704885

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 a determiner that determines a subject under observation based on an input image, wherein the R tone curve is 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, 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, 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 B 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, the G tone curve and the B tone curve are identical, the high range of the R signal includes a range higher than the middle ranges of the G and B signals, the middle range of each of the G and B signals overlaps the high range of the R signal, the electronic endo scope signal-processing device is provided with a colonoscope configured to observe a large intestine, and receives the R, G and B signals from an image obtained by photographing the large intestine, when the determiner determines that the subject under observation is the large intestine, the gradation compensation processor compensates for R, G and B gradations, and when the determiner determines that the subject under observation is an esophagus, the gradation compensation processor does not change the B and G signals, and controls the R tone curve to be 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.