Image processing device, image processing program and program-recorded recording medium

The present invention provides an image processing apparatus, comprising: an image signal inputting unit 11 for inputting a plurality of image signals different from one another in exposure time, first and second level converting factor calculating units 12, 13 for calculating a level converting factor for each of the image signals, a weighting factor calculating unit 14 for calculating a weighting factor for each of the image signals; and an adding unit 17 for adding up the image signals respectively multiplied by the level converting factors multiplied by the weighting factors. The image processing apparatus thus constructed can obtain images of wide dynamic range in a simply manner as well as reduce loss of minute image information due to accumulated processing delays and computing errors.