1. An image processor that performs motion searches by referring to a first image stored in an external memory, the image processor comprising: circuitry configured to: hold a second image in a first internal memory accessible with a higher speed than the external memory, the second image being in a predetermined range of the first image and including luminance data and chrominance data, wherein the first internal memory holds, in a unit storage area, a unit luminance data piece equivalent of luminance data of 8 columns×2 rows in a pixel space or a unit chrominance data piece equivalent of chrominance data of 8 columns×4 rows a pixel space, and includes a plurality of memory banks, the memory banks being configured to hold eight pieces of unit luminance data aligned in two columns by four rows separately, and hold eight pieces of unit luminance data aligned in one column by eight rows separately; read an image in a predetermined range of the second image from the first internal memory and produce a third image for rough search based on the read image; hold the third image in a second internal memory accessible with a higher speed than the external memory; read the third image from the second internal memory and perform a first motion search based on the third image; and read a fourth image in a predetermined range of the second image from the first internal memory based on the first motion search and perform a second motion search that is more detailed than the first motion search based on the fourth image, wherein results of the motion searches are used to obtain motion vectors for a video coding with a reduced latency involved in obtaining the motion vectors.