Patent ID: 7158264
Filing Date: 2007-01-02
Classification: H04N

Abstract:
1. A method of determining a threshold array for generating a gradation image, comprising the steps of: when the positions of thresholds up to a given gradation have been determined in a threshold array and the position of one or more thresholds of the same value for a next gradation is to be determined; (A) determining one or more candidate positions for the position of one or more thresholds of the same value for the next gradation; and (B) determining the position of a threshold for the next gradation among said candidate positions; (1) determining a particular frequency component of image data obtained based on a threshold array in which the positions of thresholds up to the given gradation have been determined; (2) determining the intensity of said particular frequency component in each of the candidate positions; (3) determining a candidate position in which the determined intensity of said particular frequency component is weak as the position of the threshold for the next gradation; and