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 data 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 data units.