1. An image capturing device comprising: an image capturing means having a light-receiving surface arrayed on which are pixels composed of image capturing elements for outputting electrical signals at output levels responsive to received light intensity; optics capable of forming images of an imaged object on the light-receiving surface; an image shifting means for moving the position of an image on the light-receiving surface; and an image processing means for processing images captured by the image capturing means; wherein the image capturing means captures the respective images on the light-receiving surface before and after movement of the image position by the image shifting means; the image processing means has: a difference calculating section for calculating a difference between the output levels of same pixels before and after moving the image position; a summed level calculating section for sequentially summing output level differences for each pixel in a pixel line arrayed in the direction of image movement to calculate a summed level of each pixel; and an image generating section for generating images based on the summed levels of each pixel rather than the output levels of each pixel.