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 means; 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 of 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, wherein the binarizing unit converts the read data into HSV color space data, and wherein the binarizing unit outputs a binarized image obtained by performing a logical OR operation upon three binarized images, which are (1) a binarized image obtained by comparing a color value (V) component data of the HSV color space data with a threshold value, (2) a binarized image obtained by extracting an edge of the color value (V) component data of the HSV color space data by an edge detection filter, and (3) a binarized image obtained by comparing a color saturation value (S) component data of the HSV color space data with a threshold value.