An image processor executing a predetermined image process on an input image including a plurality of pixels to generate an output image includes an image-processing unit reading the input image required for generating the output image into an internal storing circuit as a reference image to execute an image process, a storing capacity determination unit determining whether or not a data size of the reference image is within a storing capacity range of the internal storing circuit, and a reference image division unit dividing the data size of the reference image when the data size of the reference image exceeds a storing capacity of the internal storing circuit by the storing capacity determination unit.