An image processing system and a projector project a calibration image onto a projection target, sense the calibration image to generate sensing information, and generate projection target region information based on the sensing information. The system and projector generate projection area information based on the sensing information, image distortion correction information based on the projection target region information and the projection area information, and correct an image signal based on the image distortion correction information so that image distortion is corrected. The system and projector project an image based on the image signal corrected by the distortion correction section, determine a first height/width ratio that indicates a height/width ratio of the projection target, generate the image distortion correction information to display an image at a first height/width ratio range and display an image at a desired height/width ratio when the first height/width ratio is not within the acceptable range.