Fast seamless skew and orientation detection in document images

Reliable and generic methods for skew detection are a necessity for any large-scale digitization projects. As one of the first processing steps, skew detection and correction has a heavy influence on all further document analysis modules, such as geometric and logical layout analysis. This paper introduces a generic, scale-independent algorithm capable of accurately detecting the global skew angle of document images within the range [-90,90] degrees. By using the same framework, the algorithm is then extended for Roman script documents so as to cope with the full range [-180,180) degrees of possible skew angles. Despite its generality, the improved algorithm is very fast and requires no explicit parameters. Experiments on a combined test set comprising around 110000 real-life images show the accuracy and robustness of the proposed method.