A method for operating a control apparatus that controls a projector includes causing the projector to project a first image on a display surface, generating brightness information based on captured image data generated by causing an image sensor to capture an image of the first image on the display surface via a bandpass filter, and generating color correction data for correcting the colors of an image projected by the projector based on the brightness information. The bandpass filter includes a first bandpass filter that transmits the red light, a second bandpass filter that transmits the green light, and a third bandpass filter that transmits the blue light, and the wavelength region of the light that the first bandpass filter transmits, the wavelength region of the light that the second bandpass filter transmits, and the wavelength region of the light that the third bandpass filter transmits are separate from one another.