Image reading method and image reading apparatus

Abstract

The image reading method and apparatus read photoelectrically an original image by an image sensor and convert an output signal of the image sensor into a digital signal. At least one of an adjusting step of a quantity of light incident upon the image sensor by a light transmittance adjusting operation in an optical path, a sensing condition control step in the image sensor, and an intensity adjusting step of the output signal from the image sensor is used and a maximum value of a signal upon being converted into the digital signal is set to be constant without recourse to the original image. The method and apparatus can attain following effects that a variable aperture is unnecessary, a shading fluctuation occurred in a light quantity adjusting operation is eliminated, and an image reading operation with a maximum use of a dynamic range of a scanner by an apparatus at low costs and at high precision can be executed, in an operation for photoelectircally reading an image.

Dependencies are inferred from the claim text.