A Histogram-Based Approach to Mathematical Line Segmentation

In document analysis line segmentation is a necessary prerequisite step for further analysing of textual components. While much work has been devoted to line segmentation of regular text documents, this work can not be easily adopted to documents that contain specialist components such as tables or mathematical expressions. In this paper we concentrate on a line segmentation technique for documents containing mathematical expressions, which, due to their two dimensional structure are often comprised of multiple distinct lines. We present an approach to line segmentation in the presence of mathematics that is based on a set of histogram measures and heuristics considering vertical and horizontal distances of characters only. The method also provides a technique to distinguish consecutive lines that are vertically overlapped but belong to different mathematical expressions. Experiments on data sets of 200 and 1000 maths pages, respectively, show a high rate of accuracy.