Patent ID: 8331644

Claim:
A document handling apparatus having a detection unit comprising: an image detection unit configured to detect images of a plurality of colors on a surface of a paper sheet in accordance with each color; and a detected information processing unit configured to process detected information from the image detection unit and determine a defacement degree of paper sheet, the detected information processing unit being configured to previously detect images of a plurality of colors by using the image detection unit with respect to each of the same type of reference paper sheet as the paper sheet and a defaced reference paper sheet which has been defaced, calculate an average value and a variance value of light intensities of each detected image, calculate an average value and a variance value of images of two or more colors in the reference paper sheet based on a subtraction, an addition or an arithmetic expression which is a combination of a subtraction and an addition of two or more colors, calculate an average value and a variance value of images of two or more colors in the defaced reference paper sheet based on a subtraction, an addition or an arithmetic expression which is a combination of a subtraction and an addition of two or more colors, select an arithmetic expression of a color whose calculated value greatly differs depending on the reference paper sheet images and the defaced reference paper sheet images, detect images of a plurality of colors of the paper sheet as the inspection target by the image detection unit, calculate an average value and a variance value of light intensities in each detected image, calculate an average value and a variance value of images of two or more colors in the paper sheet by using the selected arithmetic expression, and determine a defacement degree of the paper sheet based on a result of the calculation.