1. An image processing apparatus comprising: a compression processor which compresses a color image data; a storage device which stores the data compressed by said compression processor; an expansion processor which expands the data read from said storage device; a first background controller which controls background of the color image data not yet compressed by said compression processor; a second background controller which controls background of the image data expanded by said expansion processor; and a controller which activates either said first background controller or said second background controller.