Kuang-Chih Huang

Hadamard transform based fast codeword search algorithm for high-dimensional VQ encoding

An efficient nearest neighbor codeword search algorithm based on Hadamard transform for vector quantization is presented in This work. Four efficient elimination criteria are derived from two important inequalities based on three characteristic values in the Hadamard transform domain. Before the encoding process, all codewords in the codebook are Hadamard-transformed and sorted in the ascending order of their first elements. During the encoding process, we firstly perform the transform on the input vector and calculate its characteristic values, and initialize the current closest codeword of the input vector to be the codeword whose first element of Hadamard transform is nearest to that of the input vector, and secondly use the proposed elimination criteria to find the nearest codeword to the input vector using the up-down search mechanism near the initial best-match codeword. Experimental results demonstrate the proposed algorithm is much more efficient than most existing nearest neighbor codeword search algorithms in the case of high dimension.

Multiple description watermarking for lossy network

The paper proposes an innovative watermarking scheme based on vector quantization (VQ); it is suitable for media transmission over noisy channels with multiple description coding (MDC). Digital watermarking is one of the applicable tools that can be used to protect digital contents from illegal copying and distribution. In addition to conventional schemes that apply attacks on watermarked media, we focus our application on transmitting over noisy channels to consider both the error-resilient transmission of watermarked media, and the robustness of the watermarking algorithm. By modifying the multiple description vector quantization (MDVQ) algorithm for watermark embedding and extraction, simulation results not only demonstrate the effective transmission of a watermarked image, but reveal the robustness of the extracted watermark.

A Covert Communication Scheme for a SPIHT Based Image Multiple Description Coding System

In this paper, a covert communication scheme is proposed for a set partitioning in hierarchical trees (SPIHT) based image multiple description coding (MDC) system. Firstly, the carrier image is subsampled into four subimages. The secret information is embedded among the subimages with a discrete wavelet transform (DWT) and subsampling based method. The information embedding method is also proposed by us, which can resist not only the permutation attack but also some common image processing attacks. After the information having been embedded, the subimages are compressed by the SPIHT algorithm, and one subimage corresponds to one SPIHT stream. Then the SPIHT streams are packed and transmitted through the packet based channels individually. If there are packets lost, the lost packets can be substituted by the packets which reside in the other SPIHT streams. At the receiver side, the inverse procedures are performed to recover the carrier image and the secrete information.

A Covert Communication Scheme for the DCT Based Image Multiple Description Coding System

In this paper, a covert communication scheme is proposed for a set partitioning in hierarchical trees (SPIHT) based image multiple description coding (MDC) system. Firstly, the carrier image is subsampled into four subimages. The secret information is embedded among the subimages with a discrete wavelet transform (DWT) and subsampling based method. The information embedding method is also proposed by us, which can resist not only the permutation attack but also some common image processing attacks. After the information having been embedded, the subimages are compressed by the SPIHT algorithm, and one subimage corresponds to one SPIHT stream. Then the SPIHT streams are packed and transmitted through the packet based channels individually. If there are packets lost, the lost packets can be substituted by the packets which reside in the other SPIHT streams. At the receiver side, the inverse procedures are performed to recover the carrier image and the secrete information.

Multiple description multi-watermarking with tabu search approaches

Digital watermarking is one of the useful solutions for digital rights management systems, and it is also a popular research topic in the last decade. However, most watermarking related literature focus on how to resist intentional attacks by applying benchmarks to watermarked media to estimate the effectiveness of the watermarking algorithm. Only a few papers concentrate on the errorresilient transmission of watermarked media. In this paper, we propose an innovative algorithm on vector quantization (VQ) based image watermarking, suitable for error-resilient transmission overnoisy channels. By incorporating watermarking with multiple description coding (MDC), our propsed schemes for embedding multiple watermarks can efficiently overcome channel impairments while retaining the capability for copyright and ownership protection. In addition, we employ one optimization technique, called tabu search, to optimize both the watermarked image quality, and the robustness of the extracted watermarks. Simulations emonstrate the utility and practicability of our proposed algorithm.

A Covert Communication Scheme for the DWT and Data Partitioning Based Image Multiple Description Coding System

In this paper, a covert communication scheme is proposed for a discrete wavelet transform (DWT) and packetization based image multiple description coding (MDC) system. Firstly, the secret information is embedded in the DWT domain of the carrier image by the parity modulation based method. And then, the DWT coefficient set is divided into 3 subsets, one is the horizontal subset, another is the vertical subset, the other is the diagonal subset. Each subset is compressed with the SPIHT algorithm, and one subset corresponds to one SPIHT stream. Then the SPIHT streams are packed and transmitted through the packet based channels individually. If there are packets lost, the lost DWT coefficients can be estimated by the ones which arrived at the receiver successfully. At the receiver side, the inverse procedures are performed to recover the carrier image and the secret information.

Improved image coding with classified VQ and side-match VQ

A new scheme for vector quantization (VQ) is proposed in this paper. We employ side-match and classified criteria for designing VQ codebooks to combat blocking effects induced from high compression rates, and then we use the proposed algorithm to improve the reconstructed image quality. Simulation results demonstrate the better image quality to compare with that produced from conventional schemes objectively and subjectively, at the cost of reasonable encoding complexity.