Patent ID: 7978365

Claim:
A document type discriminating apparatus comprising: a screen pattern detection portion that detects a type of a screen pattern used in an image captured by reading a document; a period change detection portion that detects a change in a period of the screen used in the image; a sharpness detection portion that detects sharpness of an edge seen in the image; a blur detection portion that detects a blur in a color of the edge seen in the image; and a document discrimination portion that discriminates that the document is a duplicate when at least two out of four discrimination results are true, the four discrimination results being discrimination as to whether or not the type of the screen pattern detected by the screen pattern detection portion is a line screen, discrimination as to whether or not a value indicating the change in the period of the screen detected by the period change detection portion exceeds a predetermined value, discrimination as to whether or not a value indicating the sharpness of the edge detected by the sharpness detection portion is lower than a predetermined value, and discrimination as to whether or not a value indicating the blur in the color of the edge detected by the blur detection portion exceeds a predetermined value.