Patent ID: 7907169

Claim:
An electronic endoscope system used for observing living tissues inside a body cavity, comprising: an image capturing system capable of capturing at least a normal image and a fluorescence image of the living tissues; an illuminating device having a white light source emitting white light and an excitation light source that emits excitation light having a predetermined wavelength, the living tissues emitting autofluorescence when irradiated with the excitation light; at least one display device configured to display the normal image and the fluorescence image; and a brightness control system configured to adjust brightness of at least one of the normal image and the fluorescence image to reduce a brightness difference between the normal image and the fluorescence image to be displayed wherein the brightness control system includes: brightness detectors configured to detect the brightness of the normal image and the fluorescence image; a setting system configured to define a target value for the brightness of the normal image and the fluorescence image respectively; and a brightness comparing system configured to compare the brightness of at least one of the normal image and the fluorescence image with the target value defined by the setting system, the brightness control system controlling the brightness of at least one of the normal image and the fluorescence image that is displayed on the display device, which is detected by one of the brightness detectors, to be substantially equal to the target value defined by the setting system.