Tracing Handwriting on Paper Document under Video Camera

Abstract

This paper describes a system that traces handwriting on paper document under overlooking video camera. This work is motivated to capture annotations on paper documents written by ordinary pen as an input to computer. As the trajectory of the pen tip is extracted from the video, each part of the trajectory is classified as ‘pen-down’ or ‘pen-up’, according to whether the part makes a dark line. Detecting written inks is not simple when handwriting is made over printed documents. Because written inks may fall on dark regions of the document and often overlap previously written inks, simple background checking may not work on dark regions. So, we interpolated the decisions at the entering and the exiting of the dark region. The system makes two-level decisions to achieve both speed and accuracy. The classifier makes quick decisions based on local information in order not to lose pen trace. The local pen up-down decisions are corrected in the global point of view when the whole information of the writing process is available, such as when the hand is out of the view. Experimental result shows that the system detects handwritings accurately even on printed documents.