1. An image processing apparatus that generates one still image having a high pixel density from multiple images, said image processing apparatus comprising: an image extraction module that extracts the multiple images used for generation of the one still image; a deviation computation module that computes a degree of deviation between each combination of the extracted multiple images; an image selection module that selects at least two images among the extracted multiple images, based on the computed degrees of deviation, so that the computed degree of deviation is small to such an extent that the at least two images are regarded as those of the same subject; and an image composition module that combines the at least two selected images to generate the one still image having a resolution higher than that of any of the at least two images to be combined, wherein each of the modules of the image processing apparatus is executed by a microprocessor.