Image reading device selecting reading position on the basis of defective factors

Abstract

In an image reading device, a reading unit reads information at a reading position. The reading position is selected from lines arranged in a prescribed range in a sub-scanning direction. A processor detects whether there is a defective pixel in one line worth of pixels and stores a position of the detected defective pixel as a defective position in a storing unit. The processor calculates defective factors for normal positions. Each of the normal positions indicates one of the plurality of lines having no defective pixel. The closer a distance between the normal position and a defective position positioned within a specific range from the normal position is, the larger a defective factor of the normal position is set. The processor sets a position having a smallest defective factor from among the normal positions. The reading unit reads the original conveyed by the sheet conveying unit at the set position.