The present invention is an image processing apparatus comprising: dividing means for dividing an image signal obtained by scanning an original document into predetermined local blocks and output a predetermined including a target pixel; a binary coding processing section which converts the image signal in the predetermined block into binary code information; means for calculating each area (dimension) of the binary values; means for calculating number of times that the binary values are changed; a threshold processing section for performing threshold processing by properly and selectively using a threshold of the maximum density difference in the predetermined area, each area (dimension) value after binary coding and number of counts as a parameter; and a judgement processing section for judging the image signal in the predetermined area.