To display an output image which is properly corrected according to specifications of various input images.

A scaling processing part 14 recognizes the size of a region (sub-image) where an image displayed by the input image signal is formed in an image formation panel 12. A panel image generating part 15 is made to generate an image signal in which a sub-image after scaling processing is superposed with the pattern image generated by a pattern image generating part 20. A user can reconfigure a projection range by deforming a pattern image so that the sub-image in the projection image is of a desired size, shape, and position. A sub-image region correcting part 21 executes two-dimension projection conversion processing for projecting the sub-image to a region corresponding to the projection range of a panel image, and causes the panel image generating part 15 to generate the image signal for outputting the image after conversion.