Image processing apparatus, image processing method, and storage medium

An image processing method comprising:

• generating halftone image data with a first resolution by performing halftone processing based on a result of comparison between a pixel value of a pixel for image data having the first resolution and a threshold value of a dither matrix;
• and
• converting the first resolution of the halftone image data into a second resolution which is half of the first resolution,
• wherein the dither matrix is composed of a plurality of columns aligned along a main scanning direction and a plurality of rows aligned along a sub scanning direction, each of the columns and each of the rows including a plurality of threshold values having multivalues, the plurality of columns including at least one column having duplicated threshold values and the plurality of rows including at least an odd-number row and an even-number row having the same duplicated threshold values.

A non-transitory computer readable storage medium storing a program for causing a computer to perform an image processing method comprising:

• generating halftone image data with a first resolution by performing halftone processing based on a result of comparison between a pixel value of a pixel for image data having the first resolution and a threshold value of a dither matrix;
• and
• converting the first resolution of the halftone image data into a second resolution which is half of the first resolution,
• wherein the dither matrix is composed of a plurality of columns aligned along a main scanning direction and a plurality of rows aligned along a sub scanning direction, each of the columns and each of the rows including a plurality of threshold values having multivalues, the plurality of columns including at least one column having duplicated threshold values and the plurality of rows including at least an odd-number row and an even-number row having the same duplicated threshold values.