Radiation images of an object, which have been recorded on recording media and in which different images of at least part of the object are embedded, are read out from the recording media, and a plurality of original image signals, each of which is made up of a series of image signal components, are thereby obtained. The image signal components of the original image signals, which represent corresponding picture elements in the radiation images, are then subtracted from each other, and a difference signal representing an image of a specific structure of the object is thereby obtained. A smoothing process is carried out on an original image signal, and a smoothed image signal is thereby obtained. The image signal components of the original image signal and the difference signal, which represent corresponding picture elements in the images, are weighted such that the weight given to the original image signal may be made larger as the image density represented by the smoothed image signal with respect to a picture element becomes lower. The weighted image signal components are then averaged. A composite image signal obtained from the weighted averaging process is utilized for reproduction of a visible radiation image of the object.