1. An image processing apparatus comprising: an input terminal that receives a plurality of image units that are temporally or spatially continuous; an image processing unit that performs image processing on the plurality of image units by iteratively performing the image processing on subsets of the plurality of image units; and a display image generating unit that controls a display to display the plurality of image units when the image processing unit begins performing the image processing on the plurality of image units; display, at a time of a completion of intermediate processing of a subset of the plurality of image units by the image processing unit, an intermediate processed image including the processed subset of the plurality of image units; and display, after completion of the processing of the plurality of image units by the image processing unit, a complete processed image including the processed plurality of image units, wherein the processing performed by the image processing unit on the plurality of image units includes extracting two similar image units having a minimum integral sum of absolute difference value from the plurality of image units, and a plurality of temporally continuous image units between the two similar image units; taking a temporally previous image unit of the two similar image units as a first image unit, taking a temporally subsequent image unit as a rear-most image unit, and connecting the first image unit and rear-most image unit; and generating a loop image made up of the first image unit and rear-most image unit, and a plurality of temporally continuous image units between the first image unit and the rear-most image unit as a processed subset of the plurality of image units.