Method and apparatus for image reading capable of detecting dust that disturbs image reading operation

摘要

An image reading apparatus which is capable of detecting a foreign particle interfering with an image reading operation includes a reference image plate, an image reading device, a peak value detector, a first memory, a comparator, and an error output controller. The reference image plate has a reference white image on the surface of the plate, and the first memory stores a first reference value. The image reading device reads such a reference white image for one line in a main scanning direction. The peak value detector detects a smallest data among the data which are included in the reference white image read by the image reading device. Then, the comparator compares the smallest data detected by the peak value detector with the first reference value. Finally, the error output controller outputs a white image error when the smallest data is smaller than the first reference value.