To allow each of a plurality of image projection apparatuses to project a required content out of a plurality of contents on a display picture.

An image transfer apparatus generates displaying image data of a plurality of windows W1 to W4 displayed on a display screen and stores the generated image data in respective storage areas A1 to A3 in a RAM which are secured for each window. The image transfer apparatus allows respective storage areas A1 to A3 to correspond to a plurality of projectors PJ1 to PJ3 in accordance with an instruction input by a user. The image transfer apparatus transfers the displaying image data of the windows W1 to W4, which are stored in respective storage areas A1 to A3, to the correlated projectors PJ1 to PJ3.