A parametric solution for optimal overlapped block motioncompensation

We find the optimal window for overlapped block motion compensation (OBMC) by statistically modeling the motion field, the field of block motion estimates and their relationship. This enables us to show how the optimal OBMC window is affected by random field parameters, such as the variance of the motion field and the correlation coefficients of both the intensity field and the motion field. The OBMC window obtained in this fashion is shown to have good performance in reducing the prediction error. Furthermore, this parametric solution provides insight into motion uncertainty and the overlapped motion compensation process.     

Fast variable-size block motion estimation for efficient H.264/AVC encoding

In this paper, an efficient algorithm is proposed to reduce the computational complexity of variable-size block-matching motion estimation. We first investigate features of multiple candidate search centers, adaptive initial-blocksizes, search patterns, and search step-sizes, to match different motion characteristics and block-sizes. To avoid being trapped in local minima, the proposed algorithm uses multiple candidate motion vectors, which are obtained from different block-sizes. To further reduce the computation cost, a threshold-based early stop strategy according to the quantization parameter is suggested. With adaptive initial block-sizes, a merge-or-skip strategy is also proposed to reduce the computation for the final block-size decision. For the H.264/AVC encoder, simulations show that the proposed algorithms can speed up about 2.6–3.9 times of the original JM v6.1d encoder, which uses fast full-search for all block-sizes, and still maintain a comparable rate-distortion performance.     

New bit rate reduction techniques for block truncation coding

Two simple and fast block truncation coding algorithms which require reduced bit rates are presented in this paper. The proposed algorithms are compared with the modified block truncation coding technique (MBTC) with regard to the mean square error (MSE), bit rates and subjective quality of the reconstructed images. It is found that the results obtained with the proposed algorithms at reduced bit rates are comparable to those obtained with the MBTC. Further, it is shown that one of the proposed algorithms yields results which are comparable to those achieved with more complex hybrid algorithms     

Shaping using variable-size regions

Constellation shaping is extended to provide shaping gains without resorting to high-dimensional constellations. This is accomplished by dividing the constellation into unequally sized constellations, and selecting these constellations on an equiprobable basis. A design example is provided, demonstrating the simplicity and power of the approach     

Closed-form connectivity-preserving solutions for motioncompensation using 2-D meshes

Motion compensation using two-dimensional (2-D) mesh models requires computation of the parameters of a spatial transformation for each mesh element (patch). It is well known that the parameters of an affine (bilinear or perspective) mapping can be uniquely estimated from three (four) point correspondences (at the vertices of a triangular or quadrilateral mesh element). On the other hand, overdetermined solutions using more than the required minimum number of point correspondences provide increased robustness against correspondence-estimation errors, however, this necessitates special consideration to preserve mesh-connectivity. This paper presents closed-form, overdetermined solutions for least squares estimation of affine motion parameters for a triangular mesh, which preserve mesh-connectivity using patch-based or node-based connectivity constraints. In particular, four new algorithms are presented: patch-constrained methods using point correspondences or spatio-temporal intensity gradients, and node-constrained methods using point correspondences or spatio-temporal intensity gradients. The methods using point correspondences can be viewed as postprocessing of a dense motion field for best representation in terms of a set of irregularly spaced samples. The methods that are based on spatio-temporal intensity gradients offer closed-form solutions for direct estimation of the best node-point motion vectors (equivalently the best transformation parameters). We show that the performance of the proposed closed-form solutions are comparable to those of the alternative search-based solutions at a fraction of the computational cost.     

Optimal windowing for wideband linear arrays

The problem of constructing a wideband beam pattern that is concentrated in both angle and frequency is discussed. This paper is a direct extension of the work of Slepian and co-workers on time- and frequency-limited functions. It is shown that the singular vectors and singular functions of the mapping relating the set of weights of a linear wideband array to its far-field directivity pattern have both concentration properties and double orthogonality properties and so they can be thought of as the wideband equivalents of the discrete prolate spheroidal sequences and wave functions. These singular functions are used to obtain approximations to a frequency-invariant beam pattern.     

Multiscale video representation using multiresolution motioncompensation and wavelet decomposition

A multiscale video representation using wavelet decomposition and variable-block-size multiresolution motion estimation (MRME) is presented. The multiresolution/multifrequency nature of the discrete wavelet transform makes it an ideal tool for representing video sources with different resolutions and scan formats. The proposed variable-block-size MRME scheme utilizes motion correlation among different scaled subbands and adapts to their importance at different layers. The algorithm is well suited for interframe HDTV coding applications and facilitates conversions and interactions between different video coding standards. Four scenarios for the proposed motion-compensated coding schemes are compared. A pel-recursive motion estimation scheme is implemented in a multiresolution form. The proposed approach appears suitable for the broadcast environment where various standards may coexist simultaneously     

Optimal two-term offset windowing for fractional delay

Fractional-sample delay in discrete-time systems is often provided by special FIR filters which are asymmetric about mid-sequence. Here we preserve the appeal of sine-sequence fractional delayers (simplicity and single-parameter delay tuning) by devising a two-term raised-cosine window which delivers fractional-delay filters comparable to the best obtainable by highly regarded optimisation approaches     

红外焦平面器件开窗寻址电路的设计

基于可综合风格的Verilog HDL技术,采取控制单元与数据通道分离的设计结构,对320×256红外焦平面阵列的开窗寻址电路进行RTL级建模,设计了具有对红外焦平面阵列任意开窗寻址功能和读出顺序可上下左右翻转功能的寻址电路。并在Cadence NC Verilog环境下进行编译与仿真,仿真结果表明整个设计能够实现预期寻址功能,满足IRFPA读出多样化的需求。     

A 170-MHz CMOS pixel processor for windowing graphics

A pixel-processing RAMDAC chip, in 1.5-μm CMOS, has been designed, tested, and operated at a clock rate of over 170 MHz. The authors describe the design methodology, pipelined architecture, and delay-matched circuitry used to create the block (about 38,000 transistors) which processes the pixel words. This block provides the flexible pixel-by-pixel data manipulation needed to solve several problems encountered in windowing graphics systems of one million or more pixels per frame. The circuitry can interpret each input pixel word differently, allowing a distinct visual type and color map to be assigned to each window. Previous high-performance RAMDACs have provided only one visual type and color mapping for an entire screen, causing the colors in all but the active window to be corrupted     

Fundamental error analysis and geometric interpretation for block truncation coding techniques

Various variants and hybrid approaches evolved from the origin of Delp and Mitchell's block truncation coding (BTC) or moment preserving quantizer (MPQ) have formed a niche as an effective and simple image compression methodology with attractive coding performance achieved at moderate bitrates. As BTC is still lacking a fundamental error analysis, in this paper we present some fundamental insights regarding one-bit (or two-level) BTC's truncation error by providing mathematical analysis as well as novel geometric interpretation. We further show that the mean-square error (MSE) of Lema and Mitchell's absolute moment block truncation coding (AMBTC) is always bounded below (i.e., less than or equal to) that of BTC. Therefore, with additional advantages in computation and implementation, AMBTC is always superior. Furthermore, we developed a new adaptive equal sign position optimization (ESPO) algorithm for optimum pixel classification. Our quantization error analysis shows that incorporating the ESPO algorithm into conventional AMBTC or BTC achieves minimum MSE in either case.     

New techniques for commercial bread dough mixing

Bread dough mixing is a complex and uncertain process that involves both biological and mechanical polymerization. Although a human expert can control the mixing of dough, it is difficult to model mathematically for use in a conventional control schema. Using the results of the well-known mixograph test for gluten development, expert bakers have observed that the instantaneous mechanical power needed to mix dough has a significant relationship with the dough's gluten development and hydraulic absorption. A logical conclusion based on this observation is to measure the input electrical power for automatic control of large dough mixers. Such a control system must sense the instantaneous, three-phase input power; this signal is very noisy, nonlinear, nonstationary, and time varying. Hence, fuzzy logic is a good tool for developing an automatic control system. Such a system is described     

Simplified implementation of the windowing method for systematic and random yield calculation

To separate systematic and random yield loss, common implementations of the windowing method use an unweighted fit of the Poisson model. By comparison to a properly weighted fit of the negative binomial model, we show that the unweighted fit of the Poisson model can give highly inaccurate results, especially in the presence of clustering. The unweighted fit of the Poisson model is shown to improve by reducing the number of points included, with the best results given by the very simplest form, which uses two points only.     

Performance analysis of space time block coding techniques for indoor optical wireless systems

Indoor optical wireless systems provide an attractive alternative for realizing next generation Wireless Local Area Networks (WLANs). In this paper, the performance of diffuse optical wireless systems, employing Space Time Block Coding (STBC) techniques, is numerically investigated, accurately taking into account, the indoor channel impulse response and the characteristics of ambient light and thermal noises at the receiver. Discrete Multitone modulation (DMT) is used to mitigate the effect of intersymbol interference due to the channel?s impulse response. The performance of STBC systems, employing two transmit elements, is compared against Single Input/ Single Output (SISO) and Maximum Ratio Combining (MRC) systems operating with the same total optical transmitter power. It is shown that STBC techniques can be used to increase the capacity of diffuse optical wireless systems, improve their coverage and decrease the required optical power at the transmitter. These results demonstrate the usefulness of Multiple Input Multiple Output (MIMO) techniques in the realization of optical WLANs.     

Color image compression by moment-preserving and block truncationcoding techniques

A new color image compression technique based on moment-preserving and block truncation coding is proposed. An input image is divided into nonoverlapping blocks and each block pixel is assigned one of two representative colors, which are computed with analytic formulas derived from preserving certain moments in the block. A bit map is then generated for each block to represent the pixels' colors. Different uniformity conditions in the representative colors are also identified and utilized to save code bits. Good average compression ratios up to about 13 can be achieved, as shown by experimental results     

New constraining method for partitioned block frequency-domain adaptive filters

For adaptive filters with many taps, a short processing delay, and relative low computational complexity, the partitioned block frequency-domain adaptive filter (PBFDAF) is a good choice. The computational complexity of this algorithm is significantly reduced by using the alternated constrained PBFDAF. This particular algorithm applies gradient constraints in an alternating manner. In this paper, a serious problem in performance of the alternated constrained PBFDAF is described. Furthermore, a modification is proposed that effectively alleviates this problem. By using this modification together with a gradient constraint approximation, a new efficient alternated constrained PBFDAF is developed. Compared with the fully constrained PBFDAF, this new constraining method does not show any significant performance loss and still has a much smaller computational complexity.     

New techniques for efficiently assessing reliability of SOCs

In this paper we propose an approach to speed-up Fault Injection campaigns for the evaluation of dependability properties of complex digital systems. The approach exploits FPGA devices for system emulation, and new techniques are described, allowing emulating the effects of faults and to observe faulty behavior. Thanks to its flexibility and efficiency, the approach is suitable to be applied to SOC devices. The paper points out the flexibility of the approach, able to inject different faults of different types in custom logic, memory blocks, and processor cores. The proposed approach combines the speed of hardware-based techniques, and the flexibility of simulation-based techniques. Experimental results are provided showing that speed-up figures of up to 3 orders of magnitude with respect to state-of-the-art simulation-based techniques can be achieved.     

New techniques for efficient sliding thin-slab volume visualization

High-resolution three-dimensional (3-D) volumetric images obtained by today's radiologic imaging scanners are rich in detailed diagnostic information. Despite the many visualization techniques available to assess such images, there remains information that is challenging to uncover, such as the location of small structures (e.g., mediastinal lymph nodes, narrowed-airway regions). Recently, sliding thin-slab (STS) visualization was proposed to improve the visualization of interior structures. These STS techniques sometimes depend on user opacity specifications or extra preprocessing, and other rendering approaches that use the general STS mechanism are conceivable. We introduce two techniques for STS volume visualization. The first, a depth (perspective) rendering process, produces an unobstructed, high-contrast 3-D view of the information within a thin volume of image data. Results are a function of relative planar locations. Thus, rendered views accurately depict the internal properties that were initially captured as position and intensity. The second method produces a gradient-like view of the intensity changes in a thin volume. Results can effectively detect the occurrence and location of dramatic tissue variations, often not visually recognized otherwise. Both STS techniques exploit the concept of temporal coherence to form sequences of consecutive slabs, using information from previously computed slabs. This permits efficient real-time computation on a general-purpose computer. Further, these techniques require no preprocessing, and results are not dependent on user knowledge. Results using 3-D computed tomography chest images show the computational efficiency and visual efficacy of the new STS techniques.     

New techniques for suppression of automobile ignition noise

Automobile ignition noise is due to fast rise-time (impulsive) currents that flow in the vehicle's wiring. The major sources of these impulses are the breakdown in the distributor of the gap between the rotor and the posts, the breakdown of the spark plug gap, and the closure of the breaker points. Each of these sources can be treated individually to suppress the ignition noise. Concepts have been developed and prototypes built and tested for incorporating simple low-pass filters directly into the spark plug (by appropriate sizing of the plug's shell and inner electrode) and into the distributor. The intent of the work was to take an individual vehicle, already suppressed by the techniques used in mass production at the time (1972) in the United States, and to improve that suppression by at least 10 dB over the frequency range 30 to 500 MHz. The amount of suppression improvement obtained, determined by comparison of frequency-scanned peak field strength, ranged from about 13 dB to about20 dB depending upon the frequency. Similar improvements were obtained on a vehicle selected at random. Preliminary measurements (made only on the first vehicle) indicate no undesirable effects upon the vehicle's operation or its exhaust emissions at three conditions. The cost of incorporating these suppression techniques into mass-produced automobiles is not known exactly but is believed by the authors to be nominal.