Local Skew Angle Estimation from Background Space in Text Regions

Almost all document analysis approaches need to perform a global analysis of the page orientation as a separate process at an early stage. It would be preferable to estimate the orientation locally after page segmentation and classification, when more knowledge about the different regions is available. In this paper, a novel local skew estimation method is presented that takes advantage of the information available after flexible and efficient page segmentation and classification methods have been applied to the document image. The proposed method accurately estimates the orientation of individual text regions by efficiently analysing the arrangement of background space contained in them. No assumption is made of the existence of a uniform or dominant orientation in the document. The whole process is very efficient, as only the regions of text are considered and the points used for the angle estimation are already available as by-products of previous document analysis stages.