Method and device for correcting document image captured by image photographing device

The invention relates to a method and a device for correcting a document image captured by an image photographing device. The method comprises the steps of determining world coordinates of four top points of the document image; calculating an original width-to-height ratio of the document image according to correspondence between the world coordinates of the four top points and projective coordinates of the four top points in a projection space and characteristics of an intrinsic matrix of the image photographing device and an extrinsic matrix of the image photographing device; determining a projection transformation matrix based on the world coordinates of the four top points and the width-to-height ratio; and obtaining the corrected document image based on the determined projection transformation matrix and the document image. According to the method and the device, perspective transformation can be corrected through one captured image, and furthermore the original image is restored according to the original width-to-height ratio.