1. An image reading apparatus for reading an image on a document, the image reading apparatus comprising: a light source that irradiates the document with light; a light-source control unit that controls amount of light from the light source; a line sensor that includes a plurality of light receiving elements, a plurality of charge coupled devices, and a shift register, the plurality of light receiving elements generating electric charges on receiving reflected light reflected from the light on the document, the plurality of charge coupled devices accumulating respective electric charges generated by the plurality of light receiving elements, and the shift register receiving electric charges transferred from the plurality of charge coupled devices; an image data generating unit that generates image data according to electric charges output from the shift register; and an image analysis unit that determines whether transfer of the electric charges is normal, based on a contour reproduction status, being the status of reproduction of contours in test image data generated by reading of a test image having contours oriented intersecting an orientation whereby the plurality of light receiving elements are arranged; wherein the light-source control unit adjusts the amount of light from the light source based on the determination by the image analysis unit.