Image reading apparatus, control method thereof, and storage medium

An image reading apparatus comprising:

• a line image sensor in which reading elements for reading an image are arrayed in a predetermined direction;
• a first derivation unit configured to, based on read data acquired by reading a chart on which a plurality of dot patterns is printed with the line image sensor, derive coordinates of each of the plurality of dot patterns;
• a second derivation unit configured to derive an inclination angle of the line image sensor based on the coordinates derived by the first derivation unit;
• and
• a first calculation unit configured to calculate a first correction value for correcting the inclination of the line image sensor based on the inclination angle derived by the second derivation unit, wherein
• on the chart, the plurality of dot patterns is arranged isolatedly from one another,
• the plurality of dot patterns includes at least one dot pattern group including one reference dot pattern and a plurality of peripheral dot patterns around the reference dot pattern, and
• the plurality of peripheral dot patterns is arranged so that a sum of coordinates from reference coordinates is zero in a case where coordinates of the reference dot pattern are taken to be the reference coordinates.