IMAGE PROCESSING UNIT

摘要

PROBLEM TO BE SOLVED: To provide an image processing unit that can conduct gradation correction processing and binary error spread processing in a considerably shorter time than that of a conventional image processing unit without increasing the cost. SOLUTION: An error spread parameter setting section 2 decides a valid gradation range of received image data except a gradation range that is regarded as white or black level pixels and sets the upper limit and the lower limit of the valid gradation range as parameters on the basis of a gray level characteristic obtained by a gray level characteristic acquisition section 1. A binary error spread processing section 3 regards pixels at the outside of the valid gradation range as the upper limit or the lower limit and applies binary error spread processing to the received image data by using a prescribed value of the setting within the valid gradation range (e.g. a median in the valid gradation range) for a criterion.