DOCUMENT IDENTIFIER WHICH CAN ALSO IDENTIFY SPECIAL TICKET, IMAGE FORMING APPARATUS USING THE IDENTIFIER, IMAGE PROCESSOR, AND COPYING MACHINE

摘要

A special ticket comprises a printed part where a given expression is made by printing, and a background part where no expression is made by printing. The shape of the peripheral part of the image, namely, the shape of part of the background part, especially of peripheral part of the background part is recognized and thereby the document is judged to be a special ticket. The document image has also an outer frame part having a given shape at its periphery, and the judgement is made based on the result of the measurement of the width of the outer frame part. The width of the outer frame part is essentially the width related to the direction orthogonal to the outline of the document image.