An image reading device has an image processor that generates correction data to be used for shading correction and performs the shading correction using the correction data. The image processor generates intermediate data with a predetermined density level, generates intermediate data in different positions in the sub-scanning direction based on image signals of a first reference plate and a second reference plate disposed in the different positions, generates first and second black correction data based on the respective intermediate data, generates black correction data according to the sub-scanning direction based on both the black correction data, and performs the shading correction using the black correction data in the respective positions in the sub-scanning direction.

An image reading apparatus includes: a conveyance roller; a plurality of line image sensors; a first obtainment means that obtains coordinates of a plurality of dot patterns on the basis of read data obtained by reading a chart printed a first dot column and a second dot column; a second obtainment means that obtains a distance between coordinates of adjacent dot patterns; and a third obtainment means that obtains a correction value for reading of an image. The chart, the dot patterns of the first dot column and the dot patterns of the second dot column are arranged to be offset from each other in the conveyance direction, and the third obtainment means obtains the correction value on the basis of a conveyance direction distance between coordinates of dot patterns in the first dot column and a conveyance direction distance between coordinates of dot patterns in the second dot column.