A New Algorithm for Skew Detection of Telugu Language Document based on Principle-axis Farthest Pairs Quadrilateral (PFPQ)

Abstract

Skew detection and correction is one of the major preprocessing steps in the document analysis and understanding. In this paper we are proposing a new method called "Principle-axis farthest pairs Quadrilateral (PFPQ)" mainly for detecting skew in the Telugu language document and also in other Indian languages. One of the popular and classical languages of India is Telugu language. The Telugu language is spoken by more than 80 million people. The Telugu language consists of simple and complex characters attached with some extra marks known as "maatras" and "vatthulu". This makes the process of skewing of Telugu document is more complex when compared to other languages. The PFPQ, initially performs pre-processing and divides the text in to connected components and estimates principle axis furthest pair quadrilateral then removes the small and large portions of quadrilaterals of connected components. Then by using painting and directional smearing algorithms the PFPQ estimates the skew angle and performs the de-skew. We tested extensively the proposed algorithm with five different kinds of documents collected from various categories i.e., Newspapers, Magazines, Textbooks, handwritten documents, Social media and documents of other Indian languages. The images of these documents also contain complex categories like scientific formulas, statistical tables, trigonometric functions, images, etc. and encouraging results are obtained.

A novel method for segmenting and straightening of text lines in handwritten Telugu documents based on smearing and regression approach

“…Step 2: To estimate parameters for further steps the present papers initially derives a connected component (CC) on Telugu document using 8-connectivity neighborhood algorithm and calculates the average width(aw) and average height(ah) of all CC's [43] using following formulas.…”

“…Touching or overlapping of characters between adjacent lines at single point or multiple point's also frequent problem in handwritten documents. In the literature [1], [42][43][44][45][46][47][48] a lot of Text line segmentation methods were presented which can be broadly divided into seven major categories [1] based on Projection-based methods [12], [37], [38], [40], Smearing methods [20], [42], [42],Grouping methods [7], [15], [16], [29], [39], [41], Methods based on the Hough transform [10], [16], [24], Repulsive-attractive network method [48] , Stochastic method and Processing of overlapping and touching Components. This method well suited for printed documents which contains uniform spacing between text lines but not suitable for unconstrained handwritten documents.…”

A Hybrid Approach for Skew Detection and Correction in the Multi-script Scanned Document

“…In [5], MSLB. Subrahmanyam et al proposed a new algorithm for Skew Detection of Telugu Language Document based on Principle-axis Farthest Pairs Quadrilateral (PFPQ).…”