1. A projection display apparatus that projects images onto a screen responsive to given image data, comprising: an image extraction section that extracts at least a portion of given first image data as an extraction image; an extraction image memory for storing extraction image data representing the extraction image; an image overlay section that generates overlaid image data by superimposing the extraction image on original image represented by given second image data; a light modulation unit that is driven responsive to the overlaid image data pixel by pixel; and an optical system for projecting onto the screen the overlaid image obtained by the light modulation unit.