Threshold matrix generating method

An image processing apparatus for printing an image on a print medium by printing a first dot pattern and a second dot pattern on the print medium in an overlapping manner, the image processing apparatus comprising:

• a first obtaining unit configured to obtain the first dot pattern by quantizing multi-valued grayscale values by using a first threshold matrix;
• a second obtaining unit configured to obtain the second dot pattern by quantizing multi-valued grayscale values by using a second threshold matrix;
• and
• a storage unit configured to store the first threshold matrix and the second threshold matrix, wherein
• the first threshold matrix and the second threshold matrix are generated according to a threshold matrix generating method and stored in the storage unit, the threshold matrix generating method including:
• 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.