Locating and recognizing multiple human actions by searching for maximum score subsequences

Abstract

Despite the numerous methods to recognize human actions in a video, few are designed for videos containing more than one action over a certain time period. Moreover, existing multiple action recognition methods adopt windowed sequence search strategy. Windowed sequence searching requires an exhaustive trial of window length yielding intensive computation. This work presents a frame-based strategy, capable of searching for maximum score subsequences that correspond to actions. Therefore, start and ending times of all actions are located, and action categories are identified as well. Moreover, contrast mutual information is proposed as a new score function to increase recognition accuracy. Experimental results indicate that the proposed method locates and recognizes multiple actions in a video accurately, even for the conventional single action classification problem.