IMAGE SYNTHESIS APPARATUS, IMAGE PICKUP APPARATUS, IMAGE SYNTHESIS METHOD, AND PROGRAM

An image synthesis apparatus is provided. The image synthesis apparatus includes a synthesis control block configured to determine a synthesized gain from a plurality of image signals having different exposure times, and a synthesis processing block configured to synthesize a plurality of image signals by use of a synthesized gain determined by the synthesis control block. In determining the synthesized gain, the synthesis control block references a predetermined predicted image signal ratio to exclude a domain of a pixel position having an image signal improper for the determination of a synthesized gain from a subject of the synthesized gain determination.