Isolated sign language recognition using Convolutional Neural Network hand modelling and Hand Energy Image

This paper presents an isolated sign language recognition system that comprises of two main phases: hand tracking and hand representation. In the hand tracking phase, an annotated hand dataset is used to extract the hand patches to pre-train Convolutional Neural Network (CNN) hand models. The hand tracking is performed by the particle filter that combines hand motion and CNN pre-trained hand models into a joint likelihood observation model. The predicted hand position corresponds to the location of the particle with the highest joint likelihood. Based on the predicted hand position, a square hand region centered around the predicted position is segmented and serves as the input to the hand representation phase. In the hand representation phase, a compact hand representation is computed by averaging the segmented hand regions. The obtained hand representation is referred to as “Hand Energy Image (HEI)”. Quantitative and qualitative analysis show that the proposed hand tracking method is able to predict the hand positions that are closer to the ground truth. Similarly, the proposed HEI hand representation outperforms other methods in the isolated sign language recognition.