| 摘要 |
PROBLEM TO BE SOLVED: To control the generation ratio of each dot incapable of being controlled heretofore by error diffusion in a printer when multivalence ternarization or more is performed. SOLUTION: A printer is equipped with heads capable of forming dots having different dot diameters. When the proper use of these dots is performed by performing a multivalence of ternarization or more by an error diffusion method, the generation ratio of each dot is controlled by changing a threshold value corresponding to the gradation value of input data. This threshold value is experimentally, successively and approximately set so that the generation ratio of the dot coincides with a set desired value. When multivalence is performed on the basis of the threshold value set to the gradation value, the generation ratio of the dot changes smoothly on the basis of the threshold value and, therefore, the generation of a pseudo-contour can be prevented and image quality can be enhanced. |
