TONE REPRODUCING METHOD, THRESHOLD MATRIX, IMAGE PROCESSING METHOD, IMAGE PROCESSOR, PRINTER DRIVER, IMAGE FORMING APPARATUS, AND INK-JET RECORDING APPARATUS

摘要

PROBLEM TO BE SOLVED: To improve both tone gradation and resolution using a feature that fine tone gradation can not be easily conspicuous in a part of high density. SOLUTION: A tone reproducing method converts a multiple gradation image to image data of each dot binary or multiple values using a dither matrix. When a part of the multiple gradation image is changed to threshold values in a part of densities, the tone reproducing method forms it in a line base of a predetermined direction, has a high pass filter property for a part other than the base, and ranges which have the high pass filter property are made to be different according to the density. Therefore, a high density improves resolution in the image after intermediate tone processing, a low density keeps the tone gradation. Then the tone gradation and resolution can be reconciled, and the quality of the image can be improved. COPYRIGHT: (C)2008,JPO&INPIT