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; a transmission portion to transmit said composite image; a display portion to display said pick up image, wherein said region designation portion includes a position acceptance portion to accept a position of a display surface of said display portion; a facial region detection portion to detect a facial region from said pick up image; and a pattern image generation portion to generate a pattern image by replacing said detected facial region said masked region, wherein: said display portion displays an image in which said generated pattern image is superimposed onto said pick up image; and said masked region determining portion includes a change portion to change said masked region included in said pattern image based on said accepted position of said display surface.