Fast Skew Angle Detection Algorithm for Scanned Document Images

This paper makes a study on fast skew angle detection for document images. Given a document image and return the skew angle. First this algorithm computes the horizontal gradient image by the input image and then merges the characters area in the text line block, to get the valid text line by non-text area filtering, at last, statistic the text line characteristics to estimate the input image skew angle. This paper gives the processing of the algorithm. The experiment results indicate that this algorithm is accurate and effective, also with robustness. The algorithm can be applied in real- time processing system, by the more this algorithm can be applied in automatic de-skew for picture and text mixed images, layout analysis, picture and text segmentation and content-based retrieval.