The use of variable block-size motion estimation (ME), disparity estimation (DE), and multiple reference frames selection aims to improve the coding efficiency of multiview video coding (MVC), however, this is at the cost of high computational complexity of these advanced coding techniques, which are not suitable for real-time video broadcasting applications. In this paper, we propose an efficient ME and DE algorithm for reducing the computational complexity of MVC. Firstly, according to the characteristics of the coded block pattern and rate distortion (RD) cost, an early DIRECT mode decision algorithm is proposed. Then, based on the characteristics of the initial search point in the ME/DE process and the observation that the best point is center-biased, an early ME/DE termination strategy is proposed. If the ME/DE early termination is not satisfied, the ME/DE search window will be reduced by applying the optimal theory. At last, two block matching search strategies are proposed to predict the best point for the ME/DE. Experimental results show that the proposed algorithm can achieve 50.05% to 77.61%, 64.83% on average encoding time saving. Meanwhile, the RD performance degradation is negligible. Especially, the proposed algorithm can be applied to not only the odd views but also the even views.

Efficient Motion and Disparity Estimation Optimization for Low Complexity Multiview Video Coding

We present a linear method for global camera pose registration from pair wise relative poses encoded in essential matrices. Our method minimizes an approximate geometric error to enforce the triangular relationship in camera triplets. This formulation does not suffer from the typical `unbalanced scale' problem in linear methods relying on pair wise translation direction constraints, i.e. an algebraic error, nor the system degeneracy from collinear motion. In the case of three cameras, our method provides a good linear approximation of the trifocal tensor. It can be directly scaled up to register multiple cameras. The results obtained are accurate for point triangulation and can serve as a good initialization for final bundle adjustment. We evaluate the algorithm performance with different types of data and demonstrate its effectiveness. Our system produces good accuracy, robustness, and outperforms some well-known systems on efficiency.

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A Global Linear Method for Camera Pose Registration

This paper presents a novel method for cost aggregation and occlusion handling for stereo matching. In order to estimate optimal cost, given a per-pixel difference image as observed data, we define an energy function and solve the minimization problem by solving the iterative equation with the numerical method. We improve performance and increase the convergence rate by using several acceleration techniques such as the Gauss-Seidel method, the multiscale approach, and adaptive interpolation. The proposed method is computationally efficient since it does not use color segmentation or any global optimization techniques. For occlusion handling, which has not been performed effectively by any conventional cost aggregation approaches, we combine the occlusion problem with the proposed minimization scheme. Asymmetric information is used so that few additional computational loads are necessary. Experimental results show that performance is comparable to that of many state-of-the-art methods. The proposed method is in fact the most successful among all cost aggregation methods based on standard stereo test beds.

Cost Aggregation and Occlusion Handling With WLS in Stereo Matching

A device may include a display control unit to move a displayed object on a screen of a display device according to movement of the display device. The displayed object is moved to a predetermined position on the screen after the display device stops moving without any user input.

Display control device, display control method, and program

In this paper, we review recent developments in VLSI architectures and algorithms for efficient implementation of lifting based Discrete Wavelet Transform (DWT). The basic principle behind the lifting based scheme is to decompose the finite impulse response (FIR) filters in wavelet transform into a finite sequence of simple filtering steps. Lifting based DWT implementations have many advantages, and have recently been proposed for the JPEG2000 standard for image compression. Consequently, this has become an area of active research and several architectures have been proposed in recent years. In this paper, we provide a survey of these architectures for both 1-dimensional and 2-dimensional DWT. The architectures are representative of many design styles and range from highly parallel architectures to DSP-based architectures to folded architectures. We provide a systematic derivation of these architectures along with an analysis of their hardware and timing complexities.

A Survey on Lifting-based Discrete Wavelet Transform Architectures

Image dense matching based on region growth with adaptive window

In this paper, a bandwidth-efficient handoff strategy is proposed and analyzed for hierarchical cellular systems. Mobile subscribers are divided into two classes, i.e., low- and high-mobility subscribers. In our bandwidth-efficient handoff strategy, each of the originating and handoff calls of both slow and fast mobile subscribers first tries to get a channel in a microcell. Macrocells are overlaid over the microcells to handle overflowed calls. A call overflowed into a macrocell requests a take-back to the new microcell at each border crossing of the microcells. The request will be accommodated by the target microcell if there is any idle traffic channel in the cell. An analytical model is developed, and the most important performance measures such as the blocking probability of originating calls and the forced termination probability of calls are evaluated. It is shown through extensive comparisons with other candidate handoff strategies that if the total traffic load of the system is not very heavy, our scheme has the best bandwidth efficiency and can provide better quality of service for mobile subscribers without bringing too much processing expense to the system.

Performance analysis of flexible hierarchical cellular systems with a bandwidth-efficient handoff scheme

A new image rectification algorithm

This paper proposes a network coding (NC) based hybrid ARQ (HARQ) algorithm for video broadcast over wireless networks. The sender applies NC technique to combine the lost packets of different terminals, so that multiple terminals can recover their lost packets via per transmission from the sender. The proposed algorithm combines the advantage of FEC scheme and NC based ARQ scheme so as to maximize not only wireless throughput but also video quality for broadcast communication. Simulation results show that our algorithm significantly improves both wireless throughput efficiency and video quality, compared with ARQ and HARQ schemes.

A network coding based hybrid ARQ algorithm for wireless video broadcast

We present a three-dimensional (3-D) hyperspectral image compression algorithm based on zero-block coding and wavelet transforms. An efficient asymmetric 3-D wavelet transform (AT) based on the lifting technique and packet transform is used to reduce redundancies in both the spectral and spatial dimensions. The implementation via 3-D integer lifting scheme enables us to map integer-to-integer values, enabling lossy and lossless decompression from the same bit stream. To encode these coefficients after the AT, a modified 3DSPECK algorithm—asymmetric transform 3-D set-partitioning embedded block (AT-3DSPECK) is proposed. According to the distribution of energy of the transformed coefficients, the 3DSPECK's 3-D set partitioning block algorithm and the 3-D octave band partitioning scheme are efficiently combined in the proposed AT-3DSPECK algorithm. Several AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) images are used to evaluate the compression performance. Compared with the JPEG2000, AT-3DSPIHT, and 3DSPECK lossless compression techniques, the AT-3DSPECK achieves the best lossless performance. In lossy mode, the AT-3DSPECK algorithm outperforms AT-3DSPIHT and 3DSPECK at all rates. Besides the high compression performance, AT-3DSPECK supports progressive transmission. Clearly, the proposed AT-3DSPECK algorithm is a better candidate than several conventional methods.

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Chengke Wu

Papers

Image dense matching based on region growth with adaptive window

Performance analysis of flexible hierarchical cellular systems with a bandwidth-efficient handoff scheme

A new image rectification algorithm

A network coding based hybrid ARQ algorithm for wireless video broadcast

Lossy to lossless compressions of hyperspectral images using three-dimensional set partitioning algorithm