PURPOSE: To make expressing halftone possible without deteriorating the quality of a line and a character picture.
CONSTITUTION: Three picture elements, for example, which are not binarized yet, are selected in the surroundings of the picture element under consideration to be binarized so as to adopt it as an area under consideration K adding the picture element under consideration. Then, reading density inside the area under consideration K is added to the total distribution difference density of the respective picture elements so as to calculate overall density I and it is divided by the binary density 255 of a black picture element so as to obtain black picture element generation probability IK. In the meantime, density order J in the area under consideration K of the picture element under consideration G is detected. When they meet a black picture element judgement condition being IK≥1.5 and J meets a first order, the picture element under consideration is forcibly made to be the black picture element. It is forcibly made into the white picture element or the black picture element in a part with rapid density change so that there is no black picture element omission in the line or the character picture. In the part with moderate density change, the same processing as the conventional one is executed so that halftone is faithfully reproduced.
SUZUKI TOMOHIRO
SUZUKI TAKAYUKI
