A reading device including a reader, a position reference member, and circuitry. The position reference member has a reference pattern along a first direction of the position reference member. The circuitry is configured to detect the reference pattern of the position reference member; determine coordinates of at least two pixels in the second direction, based on the detected reference pattern; calculate a first correction value based on the coordinates determined for the at least two pixels of the reader in the second direction; detect an outer shape and a position of an image pattern on the conveyed object based on data read by the reader; obtain a difference between an image of the conveyed object, of which a shape has been corrected, and an image of the conveyed object, of which a shape has not been correction; and set a second correction value based on the obtained difference.