Liquid discharge apparatus, liquid discharge method, and storage medium

A liquid discharge method comprising:

• moving a recording head relative to a recording medium in a main scanning direction while causing the recording head to discharge a liquid onto the recording medium to perform a main scanning movement operation;
• moving one of the recording head and the recording medium relative to another one of the recording head and the recording medium in a sub-scanning direction orthogonal to the main scanning direction while causing the recording head not to discharge the liquid to perform a sub-scanning movement operation;
• alternately repeating the main scanning movement operation and the sub-scanning movement operation to perform a multi-pass printing process including a plurality of main scanning movement operations and a plurality of sub-scanning movement operations;
• converting input data to dot data including two or more types of dots;
• changing a selective-discharge mask having two or more bits in accordance with types of the two or more types of dots;
• converting the dot data to scan data for each of the plurality of main scanning movement operations of the multi-pass printing process using the dot data and the selective-discharge mask;
• transferring the scan data to the recording head to cause the recording head to discharge the liquid according to the scan data to print an image;
• and
• applying a first selective-discharge mask to the two or more types of dots in a first gradation region of the image to convert the dot data into the scan data, and
• the first selective-discharge mask is configured to cause the recording head to
• discharge the liquid as having a first discharge amount at each of end portions of the recording head, and
• discharge the liquid as having a second discharge amount larger than the first discharge amount at a center portion of the recording head between the end portions of the recording head.

A non-transitory storage medium storing a plurality of instructions which, when executed by one or more processors, causes the one or more processors to perform a method, comprising:

• moving a recording head relative to a recording medium in a main scanning direction while causing the recording head to discharge a liquid onto the recording medium to perform a main scanning movement operation;
• moving one of the recording head and the recording medium relative to another one of the recording head and the recording medium in a sub-scanning direction orthogonal to the main scanning direction while causing the recording head not to discharge the liquid to perform a sub-scanning movement operation;
• alternately repeating the main scanning movement operation and the sub-scanning movement operation to perform a multi-pass printing process including a plurality of main scanning movement operations and a plurality of sub-scanning movement operations;
• converting input data to dot data including two or more types of dots;
• changing a selective-discharge mask having two or more bits in accordance with types of the two or more types of dots;
• converting the dot data to scan data for each of the plurality of main scanning movement operations of the multi-pass printing process using the dot data and the selective-discharge mask;
• transferring the scan data to the recording head to cause the recording head to discharge the liquid according to the scan data to print an image;
• and
• applying a first selective-discharge mask to the two or more types of dots in a first gradation region of the image to convert the dot data into the scan data, and
• the first selective-discharge mask is configured to cause the recording head to
• discharge the liquid as having a first discharge amount at each of end portions of the recording head and
• discharge the liquid as having a second discharge amount larger than the first discharge amount at a center portion between the end portions of the recording head.