Patent ID: 8668636

Claim:
An electronic endoscope system comprising: an illuminating device for projecting illumination light toward subject tissues inside a body cavity that include blood vessels, said illumination light including first to third narrowband rays, or having a wavelength range including all of the wavelength ranges of the first to third narrowband rays, at least one of the first and second narrowband rays having a central wavelength of not more than 450 nm, each of the first and second narrowband rays including such wavelengths, at which light absorbance in oxygenated hemoglobin differs from light absorbance in reduced hemoglobin that is not combined with oxygen, and the third narrowband rays having a wavelength range different from those of the first and second narrowband rays; an electronic endoscope having an imaging device for capturing and outputting image signals that represent luminance of said illumination light as being projected toward and then reflected from said subject tissues; a narrowband signal obtaining device for obtaining first to third narrowband signals from said image signals, the first to third narrowband signals corresponding to the first to third narrowband rays respectively; a luminance ratio calculator for calculating a first luminance ratio between the first and third narrowband signals and a second luminance ratio between the second and third narrowband signals; a first storage device previously storing correlations between the first and second luminance ratios and the vessel depth and the oxygen saturation; and a vascular information acquiring device for acquiring vascular information including both information about vessel depth and information about oxygen saturation representative of the percentage of oxygenated hemoglobin in the blood vessels based on the first and second luminance ratios calculated by said luminance ratio calculator by referring to the correlations stored in said first storage device.