An image processing apparatus according to the present disclosure includes: one or more image processing modules; a first work memory disposed in a previous position to the one or more image processing modules; a second work memory disposed in a next position to the one or more image processing modules; a decompression-rotation processing module configured to (a) read out and decompress plural pieces of compressed sub-band data of plural sub-bands which locate in plural bands at an identical position in a primary scanning direction, (b) rotate respective pieces of decompressed sub-band data, and store the pieces of rotated sub-band data in the first work memory; and a rotation-compression processing module configured to (c) read out the plural pieces of image-processed sub-band data stored in the second work memory and rotate the respective pieces of sub-band data, and (d) compress the respective pieces of rotated sub-band data.