To provide an image processing system, projector, information storage medium and black and white extension processing method which can improve the quality of image when at least one of white extension and black extension is performed to video signals, a extension degree setting section is controlled by using a control section to change a degree of extension only when a change-over of scenes occurs, and luminance values of R-signals, G-signals and B-signals are extended toward one of white and black sides with the degree of extension set by the extension degree setting section by using extending sections and a luminance changing section.