An Improved Analysis Approach of Overbrace/Underbrace Structure in Printed Mathematical Expressions

In printed mathematical expression recognition, structural analysis is a key step which determines the overall recognition results. As a special structure in expressions, overbrace/underbrace structure becomes a major difficulty of structural analysis as they´re difficult to be distinguished from other structures. On the basis of baseline analysis method of expression structures, this paper presents an improved approach of overbrace/underbrace structure combining region location with variable thresholds. This approach introduces overrun threshold of overbrace/underbrace symbol, which is combined with other features to establish the analysis rules and optimized by testing on a variety of overbrace/underbrace structures. The experimental results show that the approach is effective in determining and analyzing overbrace/underbrace structure.