Scanner, image forming apparatus, and image compensating method of scanner

An image forming apparatus comprising:

• a scanner which scans a manuscript;
• and
• a printer which forms an image of the manuscript scanned by the scanner on a printing medium,
• wherein the scanner includes
• a transporting unit which transports the manuscript and passes the manuscript through a preset image reading position;
• an image reading unit which outputs a scan image obtained by sequentially line-scanning the manuscript passing through the image reading position;
• at least two actuators which are isolated from each other in a horizontal direction with respect to a manuscript transport direction, each having a first end portion which is movable with interference with the manuscript being transported and a second end portion which is placed on a scanning line scanned by the image reading unit and is movable in interlock with the first end portion;
• and
• an image processing unit which reads images for skew detection which are formed in the scan image by the movement of the second end portions.

A method of outputting a compensated scan image in an image forming apparatus, the method comprising:

• transporting a manuscript;
• line-scanning the manuscript;
• generating a scan image from the line-scanned manuscript;
• reading images for skew detection from the scan image;
• calculating a skew angle based on the images for skew detection;
• and
• compensating selectively the scan image based on the skew angle, and outputting the compensated scan image.