1. An image processing apparatus for extracting a document area, comprising: a reading unit for reading a document; a binarizing unit for binarizing read data acquired by the reading unit; a labeling unit for providing a same label number to adjacent black pixels that form a group of black pixels, the label number provided to each group of black pixels being unique, the black pixels being included in the read data binarized by the binarizing unit; a noise removing unit for, when the number of black pixels in a group of black pixels counted on the basis of the unique label number is less than a predetermined number, determining that the black pixels provided with the unique label number are noise and removing the black pixels provided with the unique label number from targets to be processed; a coordinate acquiring unit for acquiring coordinate information on at least one of black pixels that remain after noise has been removed by the noise removing unit; and an extracting unit for extracting a document area on the basis of the coordinate information acquired by the coordinate acquiring unit.