To excellently rotate read image data and to reduce the size of a page memory for storing data after image processing.

Image data for one page of an original read by a scanner 10 are divided into a plurality of image data blocks, then compressed and stored in a compression memory 14, the compressed image data are extracted from the compression memory 14 in the order of image data blocks arrayed in the main scanning direction of a reproduction image PG, and decompressed and rotated decompressed image data are stored in a page memory 20. When the decompressed image data for one line of image data blocks arrayed in the main scanning direction of the reproduction image PG are stored in the page memory 20, the decompressed image data are extracted from the page memory 20, and printing operation is provided.