Patent ID: 8085443

Claim:
An original reading device that moves an original by a sheet-through method and generates image data corresponding to an image of the original, comprising: a plurality of background plates having mutually different densities; a background plate switcher operable to automatically switch between the plurality of background plates one-by-one and in order, so as to be a background at a reading position in the sheet-through method; a reader operable to (i) generate a correction data piece for each of the background plates by, when the original is located away from the reading position, performing an image reading operation each time the switcher switches between the background plates, and (ii) generate the image data by reading the image of the original by the sheet-through method when the original has reached the reading position; a detector operable to, based on the correction data pieces for the background plates, detect a noise address indicating a generation position where line noise is generated continuously in a moving direction of the original due to a dirtiness source on an original platen during original reading; a calculator operable to calculate a background visibility rate and a density component value based on the correction data pieces for the background plates, the background visibility rate indicating a degree to which a background image can be seen through the dirtiness source inferred to exist at an area of the reading position that corresponds to the detected noise address, and the density component value indicating a value of a component of light that is not influenced by the background image; and a corrector operable to correct a line noise portion of the image data with use of the background visibility rate and the density component value, the line noise portion being indicated by the detected noise address.