Image reading apparatus and image forming apparatus

摘要

An image reading apparatus includes: a driving unit that drives a photoelectric conversion element by a clock; a signal generating unit that generates an analog signal; an amplification inversion unit that amplifies an alternating current component of the analog signal with an amplification factor by a setting value that is set from outside, and that switches the alternating current component between inversion and non-inversion; a signal superimposing unit that superimposes the analog image signal on an analog signal that is output from the amplification inversion unit; and a controlling unit that converts analog image signal that is superimposed by the signal superimposing unit into a digital image signal by using the analog-digital converter, and that controls the amplification factor and the inversion and non-inversion of the amplification inversion unit based on a feature amount that appears on the digital image signal.