1. An image processing device comprising: acquisition unit for acquiring a plurality of projection images which are captured at different incident angles by irradiating a subject that is positioned between a radiation detector and a radiation emitting unit and of which a tomographic image is to be generated with radiation at different incident angles with respect to a direction normal to a tomographic plane of the tomographic image in a predetermined range while moving the radiation emitting unit; first tomographic image generation unit for generating a first tomographic image which is emphasized according to a spatial frequency and is used for radiographic interpretation, on the basis of the projection images acquired by the acquisition unit; second tomographic image generation unit for generating a second tomographic image which is emphasized according to the spatial frequency and on which the degree of emphasis is different from the degree of emphasis on the first tomographic image, on the basis of the projection images; and two-dimensional image generation unit for combining a plurality of the second tomographic images generated by the second tomographic image generation unit to generate a composite two-dimensional image.