Patent ID: 8917423

Claim:
An image scanner, comprising: a light source configured to irradiate a document with light; an image sensor configured to photo-electrically convert reflected light from the document irradiated with light by the light source; an A/D converter configured to convert an analog image signal output from the image sensor into a digital signal to output the digital signal; a lighting control unit configured to adjust, in a period other than a document scanning period, a lighting period of the light source so that the light source is turned on and off alternately in a repetitive manner in units of a line cycle, wherein the lighting control unit is configured to perform control so that the 1 ighting period and the non-lighting period that are predetermined arbitrarily in units of a line are repeated periodically in the period other than the document scanning period; a black correction unit configured to generate reference black data used for black correction based on effective pixel data in a light source non-lighting period in the period other than the document scanning period; and a white correction unit configured to generate shading data used for shading correction based on effective pixel data in a light source lighting period in the period other than the document scanning period.