An image processing apparatus for compressing and decompressing image data is disclosed that is capable of image processing with a small memory area. The image processing apparatus includes a compression unit to compress the image data to a predetermined compression format; an omission secondary compression unit to omit a portion of the compressed image data given by the compression unit, divide the compressed image data into blocks having predetermined block sizes, and perform secondary compression to generate omission secondary compression image data; a data recovery unit to recover the omission secondary compression image data into the compressed image data; an image rotation unit to rotate the compressed image data decompressed by the data decompression unit according to the block sizes; a block storage unit to store the rotated compressed image data in units of the block sizes; and a data decompression unit to decompress the compressed image data stored in the block storage unit according to predetermined conditions.