an image detection and background processing device and method having a image reader for reading a whole document and converting the read document to a digital image data of multi value . the image forming apparatus detects the density of a background in the document based on the digital image data obtained by the image reader , sets a reference value based on the background density as well as the distribution of the digital image data , and distinguishes an image area of the document from the background by comparing the reference value and the image data so as to execute a process concerning the distinguished image area . the apparatus and method includes analysis capability for determining whether the background area can be accurately discriminated from the image area based on image data .