1. An image acquisition and display method for obtaining an ordinary image captured by projecting illumination light onto an observation area and receiving reflection light reflected from the observation area and a special image captured by projecting special light onto the observation area and receiving light emitted from the observation area, and displaying the obtained ordinary and special images, the method comprising the steps of: identifying, based on the special image, a prescribed region of interest in the special image; determining a boundary line of an area which includes a region in the ordinary image corresponding to the identified region of interest and a predetermined margin added to the region; and displaying a boundary line of the region and the boundary line of the area in the ordinary image.