Method and device for generating threshold matrix for determining state of formation of dots composing output image, quantizer comprising threshold matrix for generating output image data, and image forming device and storage device comprising threshold matrix

Abstract

A threshold matrix generating method includes: generating q(x, y, g) in which the number of dots in an initial dot pattern is varied; calculating an error matrix (ERR(x, y, g)) of q(x, y, g); calculating AVE(a, b) representing the uniformity of the number of dots in discrete blocks into which the dot pattern has been divided; determining two pixels, of which the dot positions are to be swapped, on the basis of ERR (x, y, g) and AVE(a, b); swapping the dot positions; calculating the evaluation value (MSE(n)) of q(x, y, g) after the positional swapping; and repeating the positional switch of the dots repeating the generation of q(x, y, g) and the positional swapping of the dots with q(x, y, g) functioning as the initial dot pattern until a q(x, y, g) satisfying MSN(n)<MSN(n−1) is obtained.