Patent ID: 7330600

Claim:
An image processing device comprising: a low-resolution image generation part generating a low resolution image from the original image, said low resolution image having a lower resolution than the original image; a feature-value calculation part calculating a feature value with respect to an original image that is a digital image; a character area extraction part performing a local adaptive binarization of each color component by performing a local adaptive threshold processing and an expansion processing to the low-resolution image so as to perform an extractive detection of a character area and extracting a character area from said original image according to said feature value; a block division part dividing said original image into blocks; a class classification part classifying pixels belonging to said character area in each of said blocks into a first class and a second class according to colors; a black-character-color/ground-color estimation part estimating a black character color and a ground color on said original image according to the pixels belonging to said character area being classified into said first class and said second class; and a tone correction part performing a tone correction to said original image according to the estimated black character color and the estimated ground color.