A skew angle detection algorithm based on maximum gradient difference

In order to resolve the problem of skew phenomenon in the handwritten document image during the scanning process, a new skew angle detection algorithm based on maximum gradient difference as well as Hough transform was proposed in the paper. Firstly, text lines are labeled by using maximum gradient difference, and then we use the method of non-text filtering to get rid of shorter text lines and dots. Finally, margin information is extracted after refining on text lines, and two-stage Hough transform is made to the margin extracted information with the strategy varying from “coarse” to “fine” strategy, calculating the skew angle of document image which is fixed by the average of several longest lines. Experiment results shows that the algorithm detects skew angles of document image more rapidly and accurately than Hough transform alone.