Abstract: A shading correction of removing a plurality of shading factors is performed. A scanner device performs a shading correction in a manner such that a low-pass filter circuit (14) extracts a broad waveform change component caused by a temperature characteristic and a temporal change in light source or sensor sensitivity as shading factors, a phase/amplitude synchronizing circuit (15) extracts a phase shift of a cycle pattern of a lens array, a first multiplying circuit (16) synthesizes the waveforms of the extracted factors so as to form a correction-purpose image signal waveform, and the correction-purpose image signal waveform is divided from an image signal waveform subjected to a dark level correction (offset).

Abstract: A shading correction of removing a plurality of shading factors is performed. A scanner device performs a shading correction in a manner such that a low-pass filter circuit (14) extracts a broad waveform change component caused by a temperature characteristic and a temporal change in light source or sensor sensitivity as shading factors, a phase/amplitude synchronizing circuit (15) extracts a phase shift of a cycle pattern of a lens array, a first multiplying circuit (16) synthesizes the waveforms of the extracted factors so as to form a correction-purpose image signal waveform, and the correction-purpose image signal waveform is divided from an image signal waveform subjected to a dark level correction (offset).