An Accurate Method for Skew Determination in Document Images
Scott Lowther, Vinod Chandran, Subramanian Sridharan · 2002
This paper presents a new Averaged Block Directional Spectrum (ABDS) technique for determining the skew angle of digitised document images. Skew determination is important because many other document analysis techniques require (near) perfectly aligned document images to work well. The technique is based on calculating the average 2D Fourier transform of blocks in a document image and using the Radon transform to find the peak in the directional spectrum. Results from experiments indicate that the new skew determination technique is highly accurate, obtaining the skew angle within 0.25 ° in 96.4 % of test images. The technique has also shown robustness to documents highly corrupted by noise or having a large number of graphical elements. 1.