IMAGE PROCESSING METHOD AND APPARATUS

PROBLEM TO BE SOLVED: To provide an image processing method and apparatus, capable of determining the degree of focusing in consideration of varying the degree of focusing with the brightness of a lighting device or the like. SOLUTION: The method includes: a second derivative image forming step in which a second derivative image is formed by differentiating twice the respective pixels in the region of objects of decision including a display of object of reading and its environmental background; an absolute mean value calculation process in which an absolute mean value is derived by arithmetically averaging the absolute values of the second derivative value of the respective pixels in the second derivative image: a density histogram forming process in which a density histogram of the region of objects of decision is formed; a density distribution width calculation process in which a threshold for classifying the density histogram into a high luminance side and a low luminance side is derived, and the density distribution width is calculated by the difference of the respective mean densities of the two classes classified by the threshold; a parameter calculation process in which the focusing degree is calculated by dividing the absolute mean value by density distribution width; and a parameter decision process in which the derived focusing degree and a predetermined threshold are compared. COPYRIGHT: (C)2011,JPO&INPIT