An image processing method of performing rasterization of a page in units of band area includes, among other things, performing, in units of band areas, rasterization based on second intermediate data stored in a first memory area for storing intermediate data and compressed raster data stored in a second memory area. The rasterization of the plurality of band areas is performed in parallel. In addition, the performing of the rasterization based on the second intermediate data and the compressed raster data includes selectively decompressing, in units of predetermined areas, a piece of the compressed raster data stored in the second memory area, in accordance with which band areas, of a plurality of band areas, are to be subject to the rasterization.

An image processing method of performing rasterization of a page in units of band area, comprises: generating first data drawing a first group of objects included in the page; storing the generated first data into a first memory area; performing, in units of band areas, rasterization based on the stored first data to generate a first raster data of the page; compressing, in units of predetermined areas, the first raster data; storing the compressed first raster data into a second memory area; deleting the first data from the first memory area; generating second data drawing a second group of objects included in the page; storing second data into the first memory area; performing, in units of band areas, rasterization based on the second data and the compressed first raster data.