An image reading device includes an image processor that generates correction data to be used for shading correction and perform the shading correction using the correction data, and a memory that stores first black correction data to be used for the shading correction in a main scanning direction in a predetermined first position in a predetermined sub-scanning direction. The image processor generates third black data based on an image signal of a second reference plate extending in the sub-scanning direction in a predetermined second position in the main scanning direction, generates black correction data according to the sub-scanning direction based on the first black correction data and the third black data, and performs the shading correction using the black correction data so as to correct density unevenness in the main scanning direction and the sub-scanning direction caused by an interference between image signals from a plurality of sensors.

There is provided a distance calculator configured to calculate an amount of displacement of an inkjet head in the main scanning direction, and an inter-pixel distance between neighboring pixels adjacent in the main scanning direction, based on read-in test pattern image data (test image data) read from an original subjected to printing based on test pattern image data printed by discharging from a plurality of nozzles, and an image processor configured to correct image data included in a received print job so as to increase, in accordance with the amount of displacement, the amount of ink to be discharged from nozzles corresponding to positive correction target pixels whose calculated inter-pixel distance exceeds an inter-pixel threshold value (a predetermined distance).

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.