Printing device, printing method, and image processing device

A method of forming a dot on a medium by a head and thus performing printing, the method comprising:

• acquiring a position of a missing dot in which the dot cannot be formed by the head despite a position where the dot is to be formed;
• performing halftone processing of generating dot data indicating whether to form a dot, using image data including a plurality of pixels having a plurality of tone values and a dither mask including a plurality of thresholds;
• searching for a threshold used in generation of a dot in a predetermined range near the missing dot, modifying a value of a change threshold, which is a threshold satisfying a search condition of being higher than a value of a target threshold, which is a threshold used at the position of the missing dot, to a value equivalent to the value of the target threshold, and providing the modified threshold for the halftone processing at the pixel corresponding to the modified threshold;
• and
• driving the head according to the dot data.

An image processing device that processes image data and converts the image data into dot data for forming a dot on a medium, the image processing device comprising:

• a halftone processing unit that performs halftone processing of generating dot data indicating whether to form a dot, using image data including a plurality of pixels having a plurality of tone values and a dither mask including a plurality of thresholds;
• a missing position acquisition unit that acquires a position of a missing dot in which the dot cannot be formed despite a position where the dot is to be formed according to the dot data;
• and
• a modification unit that searches for a threshold used in generation of a dot in a predetermined range near the missing dot, modifies a value of a change threshold, which is a threshold satisfying a search condition of being higher than a value of a target threshold, which is a threshold used at the position of the missing dot, to a value equivalent to the value of the target threshold, and provides the modified threshold for the halftone processing at the pixel corresponding to the modified threshold.