Patent ID: 8608271

Claim:
A printing apparatus for printing an image on a printing medium by scanning a printing head across a unit area of the print medium 2M times (M is an integer larger than 1), comprising: a dividing unit which divides image data of an image that should be printed in the unit area into 2M sections of image data for the 2M printing scans (Scan 1 to Scan 2M) by using a mask setting print permitted dot areas, in which dots are permitted to be printed by the printing head, included in the unit area for each of the 2M printing scans, respectively, so that plural dots of the same type of color may be printed at the same dot area by at least two printing scans; and a printing unit which prints dots in the print permitted dot areas in each of the 2M printing scans (Scan 1 to Scan 2M) according to the divided image data, wherein the mask is configured so that i) a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (M+1) and by scans performed after Scan M is larger than a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan N+1 (N is an integer differing from M and smaller than 2M) and by scans performed after Scan N in the unit area, ii) a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (M−L+1) (L is a positive integer and L≦M−2) and by scans performed after Scan (M−L) is smaller than a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (M−L+2) and by scans performed after Scan (M−L+1) in the unit area, and a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (M+L+1) and by scans performed after Scan (M+L) is larger than a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (M+L+2) and by scans performed after Scan (M+L+1) in the unit area, and iii) as for at least one combination of S and T (S and T are different and positive integers smaller than 2M), a difference between a number of the print permitted dot areas in which printing is permitted both b scans performed before Scan (S+1) and by scans performed after Scan S and a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (S+2) and by scans performed after Scan (S+1), is different from a difference between a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (T+1) and by scans performed after Scan T and a number of the print permitted dot areas in which printing is permitted both by scans performed before Scan (T+2) and by scans performed after Scan (T+1).