Image reading device, image reading method, and image forming apparatus

An image reading device comprising:

• a transport unit that transports a document having an image formed thereon to a reading position;
• a first correcting unit that is provided upstream of the reading position in a transport direction of the document and that corrects a skew of the document by coming into contact with a leading edge of the document;
• a radiating unit that radiates light to the document at the reading position;
• an image-information acquiring unit that acquires information of the image formed on the document on the basis of information of light reflected by the document;
• a skew-amount calculating unit that calculates a skew amount of the document;
• and
• a second correcting unit that corrects a skew of the image information acquired by the image-information acquiring unit on the basis of the skew amount of the document calculated by the skew-amount calculating unit,
• wherein the image reading device switches between the skew correction by the first correcting unit and the skew correction by the second correcting unit on the basis of document information, the skew amount of the document calculated by the skew-amount calculating unit, or user's selection.