Patent ID: 6987886

Claim:
An image processing device, comprising: a degree-of-white-background-likeliness detection unit configured to detect a degree of white-background likeliness in respect of a local area of an input multi-level image; and a gray-level conversion unit configured to convert a gray level of the input multi-level image according to conversion characteristics that change in response to the degree of white-background likeliness, wherein said degree-of-white-background-likeliness detection unit is an area detection unit that marks white backgrounds and boundary areas adjacent to the white backgrounds as white-background areas, and other areas as non-white-background areas, said area detection unit including: a thresholding unit configured to carry out thresholding of the input multi-level image to generate a binary image; a white-background-area detection unit configured to count white pixels in a given area of the binary image, and to mark the given area of the binary image as a white-background area or a non-white-background area in response to the count; and an expansion unit configured to spatially expand the white-background area by a predetermined number of pixels in all directions when the white-background area is detected by the white-background-area detection unit.