PROBLEM TO BE SOLVED: To provide an endoscope system capable of accurately extracting both the position and the width of a blood vessel, and to provide a processor device, a method for operating an endoscope system, and a method for operating a processor device.SOLUTION: The endoscope system includes a light source for generating illumination light, an imaging sensor for imaging an observation object irradiated with the illumination light, an image signal acquisition part for acquiring an image signal representing the observation object from the imaging sensor, a blood vessel position signal generation part 76 for using the image signal to generate a blood vessel position signal representing the position of a blood vessel of the observation object, a blood vessel width signal generation part 77 for using the image signal to generate a blood vessel width signal representing the width of the blood vessel, and a blood vessel image signal generation part 78 for using the blood vessel position signal and the blood vessel width signal to generate a blood vessel image signal representing the blood vessel.SELECTED DRAWING: Figure 5
