Aiding Manipulation of Handwritten Mathematical Expressions through Style-Preserving Morphs

We describe a technique for enhancing a user's ability to manipulate hand-printed symbolic information by automatically improving legibility and simultaneously providing immediate feedback on the system's current structural interpretation of the information. Our initial application is a handwriting-based equation editor. Once the user has written a formula, the individual hand-drawn symbols can be gradually translated and scaled to closely approximate their relative positions and sizes in a corresponding typeset version. These transformations preserve the characteristics, or style, of the original user-drawn symbols. In applying this style-preserving morph, the system improves the legibility of the user-drawn symbols by correcting alignment and scaling, and also reveals the baseline structure of the symbols that has been inferred by system. We performed a preliminary user study that indicates that this new method of feedback is a useful addition to a conventional interpretive interface. We believe this is because the style preserving morph makes it easier to understand the correspondence between the original input and interpreted output than methods that radically change the appearance of the original input.