Patent ID: 6134351
Filing Date: 2000-10-17
Classification: H04N

Abstract:
An image processing device comprising a pixel data read means, a diffusion error calculation means, a pixel data correction means, a pixel data conversion means, a condition judging means, a random number generation means, a converted data selection means, and an error calculation means, whereinsaid pixel data read means reads a piece of pixel data;said diffusion error calculation means calculates a diffusion error, by means of a predetermined operation expression, from at least one conversion error calculated by said error calculation means;said pixel data correction means corrects a gradation value of said piece of pixel data read by said pixel data read means, by adding said diffusion error to said gradation value;said pixel data conversion means converts said gradation value of said piece of pixel data corrected by said pixel data correction means by means of at least two predetermined functions, and outputs said gradation value converted by said pixel data conversion means as a converted gradation value option for each of said functions;said condition judging means decides whether a pixel corresponding to said piece of pixel data satisfies a predetermined condition;said random number generation means generates a random number;said converted data selection means selects and outputs one out of said converted gradation value options by means of said random number generated by said random number generation means as a converted gradation value in case that said condition judging means decides said predetermined condition is satisfied, and selects and outputs one out of said converted gradation value options which is closest to said gradation value of said piece of pixel data corrected by pixel data correction means as said converted gradation value in case that said condition judging means decides said predetermined condition is not satisfied; andsaid error calculation means calculates and outputs said conversion error which is a difference between said converted value output by said converted data selection means and said gradation value of said piece of pixel data corrected by said pixel data correction means.