1. An image transmission apparatus comprising: an imaging portion to output a pick up image obtained by picking up a shooting object; a region designation portion to accept designation of at least a partial region of said pick up image; a masked region determining portion to determine a masked region to mask at least a part of said pick up image based on said accepted region; a composite image generation portion to generate a composite image in which said masked region of said pick up image is converted to another image; and a transmission portion to transmit said composite image.