Audio-video based character recognition for handwritten mathematical content in classroom videos

摘要

Recognizing handwritten equations is a challenging problem, and even more so when they are written in a classroom environment. However, since videos of the handwritten text and the accompanying audio refer to the same content, a combination of video and audio based recognition has the potential to significantly improve the recognition accuracy. In this paper, using a combination of video and audio based recognizers, we focus on improving the character recognition accuracy for handwritten mathematical content in videos using audio and propose an end-to-end recognition system. The system includes components for video preprocessing, selecting the characters that may benefit from audio-video based combination, establishing a correspondence between handwritten and the spoken content, and finally combining the recognition results from the audio and video based recognizers. The current implementation of the system makes use of a modified open source text recognizer and a commercially available phonetic word spotter. For evaluation purposes, we use videos recorded in a classroom-like environment and our experiments demonstrate the significant improvements in character recognition accuracy that can be achieved using our techniques.