Jiang Gangyi

A Digital Watermarking Algorithm Based on Region of Interest for 3D Image

A digital watermarking algorithm based on depth perceptual region of interest (DP-ROI) for copyright protection of three dimension (3D) images is proposed. First, DP-ROI is defined according to the three-dimensional depth sensation of human visual system and extracted through depth image and gray image. Then, gray image is transformed with discrete cosine transformation (DCT). Several middle frequency DCT coefficients in DP-ROI are adjusted with smaller strength to embed watermark. Finally, by computing the correlation of DCT middle frequency coefficients, and blind watermark is extracted. The experimental results show that the proposed watermarking algorithm has good robustness against image processing attacks, such as JPEG compression, Gaussian noise addition through selection of watermark embedding strength.

Fast disparity estimation algorithm for stereoscopic image sequence coding

Fast and efficient disparity estimation (DE) is a key technology in stereoscopic image sequence processing. On the basis of analyzing the correlation between disparity vectors and motion vectors, a new fast disparity estimation algorithm for stereo video coding is presented in this paper. Experimental results show that, compared with the full search algorithm, the proposed algorithm can significantly reduce DE complexity while the reconstructed image quality is quite close to that of full search method.

Quality and performance evaluation of ray-space interpolation for free viewpoint video systems

Ray-space is the main technology to realize Free Viewpoint Video (FVV) systems with complicated scenes. One of the key technologies to make the ray-space feasible is interpolation. In this paper, two fast interpolation methods based on feature points and directionality detection are compared with block based matching method, and the experimental results show that the two methods improve visual quality as well as PSNRs of rendered virtual viewpoint image greatly while computational burden is also reduced significantly.

Multiple description scalable video coding based on 3D lifted wavelet transform

In this work, a new method to deal with the unconnected pixels in motion compensated temporal filtering (MCTF) is presented, which is designed to improve the performance of 3D lifted wavelet coding. Furthermore, multiple description scalable coding (MDSC) is investigated, and novel MDSC schemes based on 3D wavelet coding are proposed, using the lifting implementation of temporal filtering. The proposed MDSC schemes can avoid the mismatch problem in multiple description video coding, and have high scalability and robustness of video transmission. Experimental results showed that the proposed schemes are feasible and adequately effective.

New approach to reducing blocking effects in stereo video coding

The correlation property of blocks may be damaged in block-based image coding, and blocking effects can be induced. Some algorithms were developed for reducing the blocking effects. However, algorithms for reducing the blocking effects in video images, especially in stereo video images, should be simple and have low computational load. In this paper, causes of inducing blocking effects in stereo video coding are analyzed, and a new algorithm for reducing three types of blocking effects is presented. For the three types of blocking effects in I-frames, three filtering schemes are proposed. For the blocking effects in P-frames and B-frames, a new method of optimizing motion estimation and disparity estimation is proposed. Experimental results show that the proposed algorithm is simple and efficient.

Noise suppression algorithm in the process of high dynamic range image fusion

A high dynamic range image is generated by using multiple low dynamic range images with different exposure times. After the generation, the image noise will be further amplified, resulting in a severe degradation in the visual quality of the final high dynamic range image. In view of the problem that the generated image needs to retain the detail information of the high-lighted area in the low-exposure image and the detail information of the low-dark area in the high-exposure image and the image noise is related to the luminance, a noise suppression algorithm based on luminance partitioning and noise level estimation in the process of high dynamic range image fusion is proposed in this paper. Firstly, according to the luminance information of the image, different luminance regions of the low dynamic range image are determined. And then the overlapped blocks are used to estimate the noise level of the different luminance regions of the image, so as to guide the sparse denoising of the image. Finally, a high dynamic range image is generated by the processed low dynamic range images. The experimental results show that the proposed algorithm can effectively suppress noise, and the generated high dynamic range image has better visual quality.

Adaptive Digital Video Watermarking Algorithm for Stereo Video

Stereo video is an important developing trend of video technologies and its intellectual property rights (IPR) protection should be resolved in advance to avoid piracy. In this paper, based on our previous research work on both digital watermarking and stereo video, a novel adaptive algorithm for watermarking stereo video is proposed. The watermark information is embedded into disparity vectors of the enhancement layer. The embedding of watermark does not affect the base-layer structure and the proposed algorithm is an adaptive one which makes the degradation of the reconstructed video image quality smallest. The operation of watermarking is performed in compressed domain without the need of fully decoding of the whole compressed stream. Watermark detection can be blindly performed without the need of original stereo video sequence. Experimental results reveal that the new algorithm is fast, simple and efficient

New approach to multiple description pyramid lattice vector quantization for robust image coding

Multiple description coding (MDC) is a new approach to alleviate the problem of packet loss in image communication over erasure channels, such as Internet and wireless networks. With decomposing an image into several descriptions and transmitting them over different channels, MDC improves the reconstructed image quality with respect to losing portions of the packet. In this paper, a new image coding scheme, called as multiple description pyramid lattice vector quantization (MDPLVQ), is proposed for robust image coding, utilizing wavelet tree structure of image and two alterable quantizers to control the redundancy of MDPLVQ. Experimental results show that the presented MDPLVQ is quite efficient.

Generation of virtual intermediate views in object-based stereo video coding

A new approach to generating virtual intermediate views for stereo videoconferencing system is presented in this paper, including extraction of stereo video objects, estimation of disparity field, and generation of virtual intermediate views. A scheme of extraction of stereo video object is first given, an adaptive multi-level disparity estimation algorithm based on characteristic disparity vectors is proposed. Then, an arbitrary intermediate disparity field is obtained with disparity interpolation and the corresponding virtual intermediate view is generated. Experimental results show that the proposed method is efficient to generate virtual intermediate views.