1. An image processing apparatus, comprising: a storage unit that stores a look-up table having at least two pieces of association information for associating part of at least one first image with part of at least one second image, which is an image whose load on the brain has been adjusted compared with that of the first image and which is an image of the same object as the first image; an image accepting unit that accepts a video; a dividing unit that spatially, temporally, or spatially and temporally divides the video accepted by the image accepting unit into at least two portions, thereby acquiring at least two first spatiotemporal blocks; a mapping unit that acquires, for each of the at least two first spatiotemporal blocks acquired by the dividing unit, an associated second spatiotemporal block, using association information from among the at least two pieces of association information; and an image output unit that outputs at least one output image, which is the whole of the at least two second spatiotemporal blocks acquired by the mapping unit or a group of part of the at least two second spatiotemporal blocks acquired by the mapping unit.