1. An image processing apparatus that generates a display image to be displayed on a display screen of a display apparatus provided in a cabin of a vehicle, the display screen of the display apparatus including a one-way mirror, the image processing apparatus comprising: an image signal input that obtains a captured image signal representing a captured image captured by a camera that captures an image of surroundings of the vehicle; an image generator that generates the display image from the captured image signal; an image output that outputs the display image to the display apparatus to cause the display image to be displayed on the display screen of the display apparatus; and a processor that controls the image generator to cause a partial region of the display image to be a black image so that a portion of the display screen at which the black image is displayed functions as a mirror.