Method of calculating correction value and method of discharging liquid

A method of discharging liquid, the method comprising:

• forming a first test pattern on a medium by using a first nozzle group and a second nozzle group of a liquid discharging device including a nozzle row, in which a plurality of nozzles for discharging liquid is aligned in a predetermined direction, having the first nozzle group, the second nozzle group, and a third nozzle group;
• forming a second test pattern on the medium by using the second nozzle group and the third nozzle group of the liquid discharging device;
• setting the first test pattern in a scanner, acquiring a read-out result of a portion formed by the first nozzle group from a read-out result of the first test pattern as a first read-out gray scale value, and acquiring a read-out result of a portion formed by the second nozzle group from a read-out result of the first test pattern as a second read-out gray scale value;
• setting the second test pattern other than the first test pattern in the scanner, acquiring a read-out result of a portion formed by the second nozzle group from a read-out result of the second test pattern as a third read-out gray scale value, and acquiring a read-out result of a portion formed by the third nozzle group from a read-out result of the second test pattern as a fourth read-out gray scale value;
• calculating an average gray scale value that is an average value of the second read-out gray scale value and the third read-out gray scale value;
• calculating a correction value of the second nozzle group based on the average gray scale value;
• and
• correcting the gray scale value represented by image data by using the correction value and discharging liquid based on the corrected gray scale value by using the liquid discharging device.

A method of calculating a correction value, the method comprising:

• forming a first test pattern having a first dot row group and a second dot row group on a medium by using a liquid discharging device that alternately repeats forming a dot row, in which dots are aligned in an intersection direction, with a nozzle row, in which a plurality of nozzles for discharging liquid is aligned in a predetermined direction, and the medium relatively moved in the intersection direction intersecting the predetermined direction and relatively moving the nozzle row and the medium in the predetermined direction;
• forming a second test pattern having a second dot row group and a third dot row group on the medium by using the liquid discharging device;
• setting the first test pattern in a scanner, acquiring a read-out result of the first dot row group as a first read-out gray scale value, and acquiring a read-out result of the second dot row group as a second read-out gray scale value;
• setting the second test pattern other than the first test pattern in the scanner, acquiring a read-out result of the second dot row group as a third read-out gray scale value, and acquiring a read-out result of the third dot row group as a fourth read-out gray scale value;
• calculating an average gray scale value that is an average value of the second read-out gray scale value and the third read-out gray scale value;
• and
• calculating a correction value of the second dot row group based on the average gray scale value.