An endoscope processor including a receiver and a correction circuit block is provided. The receiver receives an image signal. The image signal corresponds to a captured subject. The image signal is generated by an imaging device. The image signal comprises a plurality of pixel signals corresponding to a plurality of pixels. A plurality of pixels forms an optical image of the subject. The correction circuit block carries out first signal processing on the pixel signals so that a representative value matches a standard value when the image signal received by the receiver is a fluorescence image signal. The representative value is calculated on the basis of a plurality of chrominance difference values corresponding to a plurality of pixel signals. The fluorescence image signal is generated when the subject is illuminated with excitation light. The excitation light makes an organ fluoresce.
