Image processing apparatus and method thereof for adding a predetermined pattern to an image

摘要

When a predetermined pattern (e.g. a pattern indicating the serial number of a copying machine) is added on an image formed on a recording paper, the image formation apparatus suppresses the appearance of fog by the addition of a predetermined pattern in the vicinity of the image. More particularly, a control circuit, which inputs and processes an image signal, estimates the leading and ending edge positions of the recording paper with respect to the transferring direction. The edge which is perpendicular to the transferring direction of the recording paper is determined based on a signal obtained from an ITOP generation circuit and a BD detector. Accordingly, an effective area for image formation on the recording paper is obtained and a modulation amount for adding the predetermined pattern is controlled in accordance with the position on the recording paper at which the predetermined pattern is added.