Patent ID: 7145694

Claim:
An image processing apparatus processing a binary image, comprising: an input unit that inputs the binary image as a multi-valued image; a halftone dot image area map creating unit controlling the image processing apparatus to search for a halftone dot image area in the multi-valued image according to a process, comprising: recognizing halftone dots in the multi-valued image, generating a list of halftone dot information comprising center-of-gravity information about centers of gravity of the halftone dots, as information about each recognized halftone dot, plotting the centers-of-gravity of the recognized halftone dots in a plot area ensured in advance, determining a shape and a size of masks to serve as search areas based upon an input resolution of the binary image, arranging the masks to include a center-of-gravity of a target halftone dot, counting a number of centers-of-gravity of the halftone dots for each of the arranged masks, determining a high possibility that noise and/or dust on the binary image may be erroneously recognized as halftone dots, if the number of the centers-of-gravity of the halftone dots is equal to or smaller than a threshold value, eliminating information about the centers-of-gravity of erroneously recognized halftone dots from the list and the plot area, and creating a halftone dot image area map according to the halftone dot information list from which the erroneously recognized halftone dot information has been eliminated; a line drawing/character area map creating unit that searches for a line drawing/character image area in the multi-valued image and creates a line drawing/character image area map; a halftone dot image binarizing unit that binarizes an input image corresponding to the halftone dot image area map created based upon the eliminating the erroneously recognized halftone dot, while suppressing input read errors occurred when said input unit inputs the binary image by optimizing a value of a target pixel to be binarized, and generates a binarized halftone dot image; a line drawing/character smoothing unit that smoothes a jaggy contained in an input image corresponding to the line drawing/character area map, and generates a binarized line drawing/character image; and an image combining unit that combines the binarized halftone dot image and the binarized line drawing/character image.