Threshold matrix generating method

A threshold matrix generating method of generating a first threshold matrix and a second threshold matrix that is used in an image processing apparatus, comprising

• a dot pattern generating step of generating a first initial pattern that is a dot pattern corresponding to a first grayscale value and a second initial pattern that is a dot pattern corresponding to a second grayscale value lower than the first grayscale value for each of a pixel region of the first threshold matrix and a pixel region of the second threshold matrix;
• and
• a threshold setting step of setting thresholds for each of the pixel regions of the first threshold matrix and the second threshold matrix based on the first initial pattern and the second initial pattern such that dot patterns having continuity with the first initial pattern and the second initial pattern are obtained at grayscale values between the first grayscale value and the second grayscale value, wherein
• a first dot pattern according to a result of quantization performed on multi-valued grayscale values by using the first threshold matrix and a second dot pattern according to a result of quantization performed on multi-valued grayscale values by using the second threshold matrix are printed on a print medium in an overlapping manner.