Image scanning apparatus, control program of the same, and storage medium for storing control program of the same

摘要

The invention provides an image scanning apparatus capable of obtaining an image signal in high quality even with existence of a non-effective picture in a scanning area. The apparatus comprises: an radiation unit for radiating scanning light onto a scanning area where an original is arranged; a photodetector for detecting an optical image formed by the scanning light which is reflected in the scanning area or transmits therethrough; a test drive unit for driving the radiation unit and the photodetector under predetermined drive condition; and an adjusting unit for adjusting the drive condition for the radiation unit and the photodetector in accordance with an output signal outputted from the photodetector by the driving. The photodetector has an overflow drain mechanism, and the adjusting unit adjusts an exposure of the photodetector at a brightest point of an effective picture of the optical image to approach its quantization exposure limit.