Xinhong Zhang

Information theory applications in error bit rate analysis of digital image watermarking

An error bit rate (EBR) analysis of digital image watermarking is proposed based on information theory. The relationship between watermarking capacity and EBR is also discussed. Two watermarking communication models are established for the EBR analysis of digital image watermarking. In the watermarking communication models, channel coding is introduced to transmit digital watermark in the watermarking channel. Another concept, watermark payload capacity, is introduced. EBR of watermarking will keep a lower lever if its payload capacity is less than the channel capacity.

Image watermarking algorithm based on the code division multiple access technique

A multiple watermarking algorithm based on the Code Division Multiple Access (CDMA) spread spectrum technique is presented. Multiple copyright identifiers are convolutional encoded and block interleaved, and the orthogonal Gold sequences are used to spread spectrum of the copyright messages. The CDMA encoded copyright messages are embedded into the wavelet sub-bands. As a blind watermarking algorithm, the copyright identifiers are extracted without the original image. The experimental results show that the proposed algorithm improves the detection BER, and the multiple copyright identifiers have preferable robustness and invisibility.

Color-Coded Imaging with Adaptive Multiscale Spatial Filtering

Digital subtraction angiography has become one of the most important approaches to artery disease diagnosis and treatment. Doctors implement diagnose and treatment by subjective analysis of the DSA series, and the results are always dependent on doctors’ experience. The application of color-coded imaging technology makes it convenient to identify images and provides additional physiology information auxiliary diagnosis and treatment. Before implementing color-coded imaging technology on DSA series, we preprocess the images with several mutiscale spatial filters to remove noises and enhance vessel structures to make the results readable and clear.

Water Molecules Diffusion in Diffusion Weighted Imaging

In the studying of fibers microstructure of brain white matter, many reconstruction methods have been proposed to interpret the diffusion-weighted signal. Those methods can be categorized into model-based and model-free methods. In this paper, the diffusion configuration of water molecules are discussed, and two questions are put forward to analyze the performance of the current algorithms about diffusion configuration.

The maximum capacity and minimum detectable capacity of information hiding in digital images

Information hiding capacity of digital image is the maximum information that can be hidden in an image. But the lower limit of information hiding, the minimum detectable information capacity is also an interesting problem. This paper proposes new method of the information hiding capacity bounds analysis that is based on the theories of attractors and attraction basin of neural network. The upper limit and lower limit of information hiding, namely the maximum information capacity and the minimum detectable information capacity are unified in a same theory frame. The results of research show that the attraction basin of neural network decides the upper limit of information hiding, and the attractors of neural network decide the lower limit of information hiding.

Information hiding and detection error rate

The information hiding capacity is the number of bits that can be hidden in a host image. This paper discusses the relationship of the information hiding capacity with the detection error rate. According to the results of research, the detection error rate of information message mainly influenced by the information average energy and the payload capacity. The error rate rises with the increase of information hiding payload capacity.