Image reading apparatus, default value adjusting method of image reading apparatus, and chart original

摘要

A chart original in which two or more patterns are disposed so as to be separated at predetermined intervals and are symmetric with respect to a second imaginary line which is orthogonal to a first imaginary line. Each of the patterns is formed from a first line segment, which is orthogonal to the first imaginary line, and two second line segments, which are disposed at opposite positions with respect to the first line segment so as to intersect the first line segment. Each of the patterns intersect the first imaginary line at three points.