Patent ID: 8279493

Claim:
An image processing method for forming print image data to be printed by an image forming apparatus configured to form multi-level dots, comprising: forming multi-level data corresponding to the multi-level dots of image data indicating a duplicated document; and generating print image data corresponding to the multi-level dots to be printed by the image forming apparatus by combining multi-level data corresponding to multi-level dots of manuscript image data with the multi-level data corresponding to the multi-level dots of the image data indicating the duplicated document in a manner such that the multi-level data corresponding to the multi-level dots of the image data indicating the duplicated document are added to the multi-level data corresponding to the multi-level dots of the manuscript image data in portions where the multi-level data corresponding to the multi-level dots of the manuscript image data indicates non-ejection, but only the multi-level data corresponding to the multi-level dots of the manuscript image data are used in a portion other than the portion where the multi-level data corresponding to the multi-level dots of the manuscript image data indicates non-ejection, wherein the multi-level dots of image data indicating the duplicated document include a dot indicating the duplicated document and a dot indicating background; the dot indicating the duplicated document has a dot size that can be reproduced by a duplicating apparatus that duplicates the manuscript image data; the dot indicating the background has a dot size that cannot be reproduced by the duplicating apparatus; a set of possible dot size values of the multi-level data corresponding to the multi-level dots of the image data and a set of possible dot size values of the multi-level data corresponding to the multi-level dots of the manuscript image data are equal, and the dot size values are expressed by a predetermined number of bits; and rasterizing is applied to data output from combining the multi-level data corresponding to the multi-level dots of manuscript image data with the multi-level data corresponding to the multi-level dots of the image data indicating the duplicated document.