Patent attributes
By reading an image of a reference plate, whether or not a likeliness that a linear abnormal image is occurred in the image of the document due to a foreign matter and the like attached on a contact glass exists is determined. In the case where there is the likeliness of occurrence of the linear abnormal image, the occurrence of the abnormal image is suppressed by changing an image reading position. At this time, a reading sensitivity is measured by reading a reference document having a single white color instead of a normal document. An adjustment data is generated according to the measurement result and stored in a memory. Then, light quantity of an exposure lamp is regulated in accordance with the document reading position by using the adjustment data.
