Patent ID: 8075077

Claim:
A method of calculating a correction value, 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; converting the first read-out gray scale value, the second read-out gray scale value, the third read-out gray scale value, and the fourth read-out gray scale value into corrected read-out gray scale values by correcting at least one between the read-out result of the first test pattern and the read-out result of the second test pattern based on a difference between the second read-out gray scale value and the third read-out gray scale value; and calculating a correction value based on the corrected read-out gray scale values.