As manner of manuscript reading, it forms the manuscript reader, the image formation device,

摘要

PPROBLEM TO BE SOLVED: To suppress the variation of original read values read from photoelectric transducers of line sensors regardless of the variation of distances of the line sensors to an original supporting plate. PSOLUTION: In a data processing unit, an average value BB is divided using a white reference read average value AA determined for each line sensor from white reference read values A resulting from reading a white reference board by photoelectric transducers of line sensors CIS22-CIS26 arrayed alternately and from white reference read values B resulting from reading another white reference board placed on an original supporting plate by the same photoelectric transducers, thereby determining, for each of the photoelectric transducers of the line sensors, a sensitivity offset coefficient C for aligning constant sensitivities that are made different by the variation of distances of the line sensors CIS22-CIS26 to the original supporting plate. Next, in shading correction for correcting an original read value E using a white reference read value Aa and a black reference read value resulting from the white reference board just before reading an original, the white reference read value Aa is corrected with the sensitivity offset coefficient C. PCOPYRIGHT: (C)2006,JPO&NCIPI