Patent ID: 8264749
Filing Date: 2012-09-11
Classification: H04N

Abstract:
1. An image reading apparatus comprising: a light emitting unit which emits light to a document; a photoelectric conversion unit which converts a quantity of light reflected from the document into an analog signal; an A/D converter which converts the analog signal to a digital signal; a clock unit which clocks an elapsed time from start-up of the light emitting unit which occurs upon a power supply being switched on; a memory including: a γ correction table in which a digital signal is corresponded to a first correction value for carrying out γ correction for the digital signal; a light-quantity calculating unit which calculates the quantity of light emitted to the document from the light emitting unit on the basis of the clocked elapsed time from a time at which the clock unit starts clocking to a time at which the light emitting unit starts emitting the light by an operation of a user by referring to the light-quantity correction table; a correction value calculating unit which calculates a second correction value for the digital signal on the basis of the quantity of light calculated by the light-quantity calculating unit and the digital signal; and a γ correction unit which corrects the digital signal on basis of the γ correction table, wherein the γ correction unit is configured to: