Chih-Ming Fu

Hand gesture recognition using a real-time tracking method and hidden Markov models ☆

Abstract In this paper, we introduce a hand gesture recognition system to recognize continuous gesture before stationary background. The system consists of four modules: a real time hand tracking and extraction, feature extraction, hidden Markov model (HMM) training, and gesture recognition. First, we apply a real-time hand tracking and extraction algorithm to trace the moving hand and extract the hand region, then we use the Fourier descriptor (FD) to characterize spatial features and the motion analysis to characterize the temporal features. We combine the spatial and temporal features of the input image sequence as our feature vector. After having extracted the feature vectors, we apply HMMs to recognize the input gesture. The gesture to be recognized is separately scored against different HMMs. The model with the highest score indicates the corresponding gesture. In the experiments, we have tested our system to recognize 20 different gestures, and the recognizing rate is above 90%.

Efficient post-compression error-resilient 3D-scalable video transmission for packet erasure channels

We propose an efficient error-resilient video transmission algorithm over packet erasure channels using optimal source and channel bit-allocation. This algorithm uses FEC and rate-distortion optimization to find the optimal allocation of source and channel bits in each quality layer. The packet loss probability is periodically reported to the video server. This method can also be incorporated with any coding structure that generates a set of independent compressed bitstreams. The algorithm efficacy is demonstrated by simulations in which the video compression is an error-resilient 3D-SPIHT algorithm and the channel protection is provided by Reed-Solomon (RS) codes.

A new error resilient video coding using matching pursuit and multiple description coding

This paper proposes a new error resilient video coding scheme using the matching pursuit (MP) residual coding and the multiple description coding. A conventional discrete cosine transform-based video coding scheme introduces undesirable blocking artifacts at low bit rates. MPs for residual coding has been developed to overcome the disadvantage. The parameters obtained after MP, called atoms, are encoded into two balanced descriptions using scalar quantizers. The two descriptions are respectively transmitted over two separate channels. If both descriptions are received, a high-quality reconstruction can be obtained, however, if either description is lost, a low-quality, but acceptable, reconstruction can be acquired.

Timing acquisition for wavelet-based multirate transmissions

The acquisition problem in wavelet-based modulation is very important. We discuss the problem of the ML-based method proposed by M. Luise et al. (see IEEE Trans. Commun., vol.48, p.1047-54, 2000) for timing acquisition and then we develop a novel acquisition algorithm. Our method uses the properties of the scaling function in the derivation of the acquisition function. We also show that the S-curve of our acquisition algorithm is smooth and has a unique zero during the signaling interval. Thus, we can acquire the correct symbol timing without ambiguity. The performance of our acquisition algorithm is evaluated by Monto-Carlo simulation using the Meyer wavelet.

Clock synchronization for fractal modulation

We propose a naive algorithm for the timing recovery for fractal modulation. We first investigate the bit error rate due to the clock error of a fractal modulation. Then, we propose clock synchronization techniques for fractal modulation. Our acquisition algorithm uses exclusively the self-similar property of fractal for signal modulation. The performance of our algorithm is also demonstrated.

A joint source and channel coding algorithm for error-resilient SPIHT-coded video bitstreams

We propose an analytical rate-distortion optimized joint source and channel coding algorithm for error-resilient scalable encoded video for lossy transmission. A video is encoded into multiple independent substreams to avoid error propagation and is assigned forward error correction (FEC) codes and source bits using Lagrange optimization. Our method separates video coding and packetization into different tiers which can be easily incorporated into any coding structure that generates a set of independent compressed bit-streams. To demonstrate the performance, we use the 2-state Markov model to describe the burst loss channel and Reed-Solomon codes as forward error correction codes. Simulation results show that the proposed channel incorporated rate-distortion optimization approach have better performance.

Combined Error Concealment and Error Correction in Rate-Distortion Analysis for Multiple Substream Transmissions

We propose a new framework for multiple scalable bitstream video communications over lossy channels. The major feature of the framework is that the encoder estimates the effects of postprocessing concealment and includes those effects in the rate-distortion analysis. Based on the framework, we develop a rate-distortion optimization algorithm to generate multiple scalable bitstreams. The algorithm maximizes the expected peak signal-to-noise ratio by optimally assigning forward error control codes and transmission schemes in a constrained bandwidth. The framework is a general approach motivated by previous methods that perform concealment in the decoder, as in our special case. Simulations show that the proposed approach can be implemented efficiently and that it outperforms previous methods by more than 2 dB

Error concealment protection for loss resilient bitplane-coded video communications

In this paper, we propose an error control scheme for video communications over lossy channels. The proposed algorithm uses error concealment protection (ECP) approach to coordinate with multiple encoded streams which is capable of handling error concealment to achieve robust transmissions. Unlike previous methods, our algorithm focuses on joint optimizing multiple substreams distortion with concealment over error prone channels. The algorithm minimizes the expected rate-distortion function to achieve the optimal FEC result. In the experiments, we demonstrate the effectiveness of our method by using a 3-D SPIHT algorithm. Simulation results show that the proposed protection strategy achieves about 2 dB higher peak signal-to-noise ratio compared to conventional method

Timing acquisition for fractal modulation in Gaussian white and 1/f channels

We propose a clock acquisition algorithm for timing recovery for fractal modulation in additive white Gaussian noise (AWGN) and 1/f channels. Our acquisition algorithm uses exclusively the data redundancy inherently built in the fractal modulation to locate the beginning of timing of all the subbands simultaneously. Different diversity techniques can then be applied after the beginning of the data block is obtained. Our acquisition functions are derived by using the maximum-likelihood method. Using a serial search algorithm to maximize the acquisition function, we may find the timing point. Simulations have been conducted in evaluating the mean acquisition time of our algorithm.

Data-aided frame timing acquisition for fractal modulation in an AWGN channel

We propose a frame timing acquisition algorithm for fractal modulation in additive white Gaussian noise (AWGN) channels. Our algorithm exclusively uses the data redundancy inherent in fractal modulation to locate the start time of all the sub-bands (start-of-frame). The acquisition functions are derived using the maximum-likelihood method and the start-of-frame that maximizes the function attained by a serial search algorithm. Monte-Carlo simulations are conducted to evaluate the mean acquisition time of our algorithm.