1. An image processing apparatus comprising: a photographing unit configured to continuously photograph a first image by first photographing with an emission by an emission unit and plural sheets of second images by second photographing without the emission; a sensitivity setting unit configured to set a sensitivity of the first photographing to be lower than a sensitivity of the second photographing; a gain processing unit configured to perform gain processing in which image data of the first image is multiplied by a gain amount; an averaging unit configured to create an averaged image based on the first image gain processed by said gain processing unit and the plural sheets of the second images; and a synthesis unit configured to create a synthesized image by synthesizing the first image photographed by said photographing unit and the averaged image created by said averaging unit.