Patent ID: 6147771
Filing Date: 2000-11-14
Classification: H04N

Abstract:
A method of adjusting an image density comprising:(a) inputting an n-bit image signal;(b) converting the n-bit image signal into an m-bit image signal larger than the n-bit image signal by a first converting processing so as to change a gray-level number;(c) converting the m-bit image signal into a t-bit image signal larger than the m-bit image signal by a gamma converting expression of a gradation gamma converting processing so as to change a gradation gamma; and(d) converting the t-bit image signal into an s-bit image signal smaller than the m-bit image signal by a second converting processing so as to again change the gray-level number;wherein the second converting processing comprises an error diffusion processing operation in which an error obtained by comparing a value of a target pixel with a prescribed value is diffused to peripheral pixels of the target pixel to thereby correct values of the peripheral pixels, and each of the corrected values of the peripheral pixels is clipped so as not to exceed a predetermined value.