Patent ID: 8657737

Claim:
An electronic endoscope system comprising: an illuminating means for illuminating a subject tissue located in a body cavity and containing a blood vessel with illumination light, an electronic endoscope including an image sensor for receiving reflected light of the illumination light emitted from the illuminating means to the subject tissue to acquire an image of the subject tissue and outputting an imaging signal representing a luminance of the reflected light, a first image data producing means for outputting a plurality of first image data having different wavelength bands from the imaging signal, a blood vessel information producing means for producing blood vessel information on the blood vessel from the first image data, a reference value region setting means for setting a given region in an image acquired by the electronic endoscope as reference value region, a reference value blood vessel information calculating means for calculating a reference value for the blood vessel information based on second image data for a region within a reference value region set by the reference value region setting means to acquire a reference value blood vessel information, a relative value blood vessel information calculating means for calculating relative value blood vessel information from a difference between the blood vessel information and the reference value blood vessel information, an image producing means for producing a relative value blood vessel information image representing a relative value of the blood vessel information in simulated color from the relative value blood vessel information, and an image displaying means for displaying a relative value blood vessel information image produced by the image producing means; wherein the imaging signal is a first narrowband signal, a second narrowband signal, and a third narrowband signal respectively corresponding to a first narrowband light, a second narrowband light, and a third narrowband light having different wavelength bands, wherein the blood vessel information is an oxygen saturation level of blood hemoglobin in the blood vessel, and wherein the reference value region setting means calculates a first luminance ratio between the first image data respectively corresponding to the first narrowband signal and the third narrowband signal and a second luminance ratio between the first image data respectively corresponding to the second narrowband signal and the third narrowband signal, further calculates blood vessel depth information from the first luminance ratio and the second luminance ratio, distinguishes between superficial-layer blood vessel region and a non-superficial-layer blood vessel region from the blood vessel depth information, and thereby sets the non-superficial-layer blood vessel region as the reference value region.