Patent ID: 7352496

Claim:
An image scanning device, comprising: a white roller to feed a document along a document transfer path; a reference white sheet spaced by a certain distance from the white roller; an image readout unit provided opposite to the white roller and the reference white sheet with respect to the document transfer path to read out image data from the document; a first storage to store an initial roller shading compensation value of a first region of the white roller and an initial sheet shading compensation value of a second region of the reference white sheet, the values being initially read out by the image readout unit; a control unit to control the image readout unit to read out the second region of the reference white sheet prior to reading out the image data so that a reference shading compensation value is generated, and to compare the generated reference shading compensation value with the initial sheet shading compensation value stored in the first storage to calculate a final shading compensation value of the first region; and an image compensation unit to compensate for the readout image data according to the calculated final shading compensation value.