Patent ID: 7261387

Claim:
An ink jet printing method to form an image on a print medium by scanning a print head over the print medium a plurality of times, wherein the print head ejects ink to form dots on the print medium according to image information made up of a matrix of pixels, each of which pixel has a multi-valued grayscale level expressed by a combination of printing and non-printing of dots in element areas making up the pixel, the ink jet printing method comprising: an allocation step of allocating a dot arrangement pattern to each pixel according to a grayscale level of the pixel, the dot arrangement pattern determining the presence or absence of a printed dot in each of the element areas making up the pixel, a plurality of dot arrangement patterns forming the matrix of the pixels; an ejection data generation step of dividing the printing of dots, which is based on the dot arrangement pattern produced by the allocation step, into a plurality of scans of the print head by using mask patterns and generating ejection data for each of the scans; and an ejection step of ejecting ink from the print head according to the ejection data generated by the ejection data generation step, wherein the mask patterns and the dot arrangement patterns are linked with each other so that the number of actually printed dots in a pixel having a predetermined grayscale level is greater than the number of dots determined by the allocation step by a predetermined number.