Shading corrections device with white color reference member peripherally providined proximate to a platen roller for feeding an original document over a glass platen

摘要

In a shading correction device of an image reading machine, for example, a Xerography unit or a thermal transfer unit, a platen roller is provided so as to engage and disengage from a platen glass. A reference white color member is provided. The reference white color member is movable up to a position between the platen glass and the platen roller along the circumferential side of the platen roller and with rotation of the platen roller.