US Patent 7907169 Electronic endoscope system for fluorescence observation

An electronic endoscope system, which is adapted to observe a fluorescence image of autofluorescence emitted from a body cavity wall irradiated with excitation light as well as a normal image of the body cavity wall illuminated with white light on a display device, includes a brightness control system configured to adjust brightness of at least one of the normal image and the fluorescence image to reduce brightness difference between the normal image and the fluorescence image to be displayed.