Rectification of Distorted Document Images Using Variants, Invariants and Normalization
Ryo Niwa, Akira Horimatsu, Masakazu Iwamura, Koichi Kise, Seiichi Uchida, Shinichiro Omachi · 2008
For user convenience, document image processing captured with a digital camera instead of a scanner has been researched. However, existing methods of document image processing are not usable for a perspectively distorted document image because most of them require a neat image captured by a scanner. Thus, we have to rectify perspective distortion of document images. For the purpose, we have proposed a layout free rectification method based on variants and invariants. In this paper, we reports two improvements on the method. The first one is to increase the stability of the method. The second one is to eliminate remaining affine distortions using prior knowledge. We confirm the effectiveness of the improvements by experiments.