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With the advent of advances in imaging and computing technologies, large-scale data acquisition and processing have become commonplace in many science and engineering disciplines. Conventional workflows for large-scale data processing usually rely on in-house or commercial software that are designed for domain-specific computing tasks. Recent advances in MapReduce, which was originally developed for batch processing textual data via a simplified programming model of the map and reduce functions, have expanded its applications to more general tasks in big-data processing, such as scientific computing, and biomedical image processing. However, as shown in previous work, volume rendering and visualization using MapReduce is still considered challenging and impractical owing to the disk-based, batch-processing nature of its computing model. In this article, contrary to this common belief, we show that the MapReduce computing model can be effectively used for interactive visualization. Our proposed system is a novel extension of Spark, one of the most popular open-source MapReduce frameworks, which offers GPU-accelerated MapReduce computing. To minimize CPU-GPU communication and overcome slow, disk-based shuffle performance, the proposed system supports GPU in-memory caching and MPI-based direct communication between compute nodes. To allow for GPU-accelerated in-situ visualization using raster graphics in Spark, we leveraged the CUDA-OpenGL interoperability, resulting in faster processing speeds by several orders of magnitude compared to conventional MapReduce systems. We demonstrate the performance of our system via several volume processing and visualization tasks, such as direct volume rendering, iso-surface extraction, and numerical simulations with in-situ visualization. [ABSTRACT FROM AUTHOR]

Forty years ago, the first General Purpose Raster Graphics Processor made the transition from research project to commercial product. This is the story of the creation of a new graphics system and the startup company that produced it in the early days of raster computer graphics. [ABSTRACT FROM AUTHOR]

Visualization designers regularly use color to encode quantitative or categorical data. However, visualizations “in the wild” often violate perceptual color design principles and may only be available as bitmap images. In this work, we contribute a method to semi-automatically extract color encodings from a bitmap visualization image. Given an image and a legend location, we classify the legend as describing either a discrete or continuous color encoding, identify the colors used, and extract legend text using OCR methods. We then combine this information to recover the specific color mapping. Users can also correct interpretation errors using an annotation interface. We evaluate our techniques using a corpus of images extracted from scientific papers and demonstrate accurate automatic inference of color mappings across a variety of chart types. In addition, we present two applications of our method: automatic recoloring to improve perceptual effectiveness, and interactive overlays to enable improved reading of static visualizations. [ABSTRACT FROM PUBLISHER]

Translucent objects such as fog, clouds, smoke, glass, ice, and liquids are pervasive in cinematic environments because they frame scenes in depth and create visually-compelling shots. Unfortunately, they are hard to render in real-time and have thus previously been rendered poorly compared to opaque surfaces. This paper introduces the first model for a real-time rasterization algorithm that can simultaneously approximate the following transparency phenomena: wavelength-varying (“colored”) transmission, translucent colored shadows, caustics, volumetric light and shadowing, partial coverage, diffusion, and refraction. All render efficiently with order-independent draw calls and low bandwidth. We include source code. [ABSTRACT FROM PUBLISHER]

A built-in self-repair (BISR) scheme for random access memories (RAMs) with 2-D redundancy has a built-in redundancy analyzer (BIRA) for allocating the redundancy. The BIRA typically has a cache-like element called local bitmap for storing the fault information temporary. In this paper, a high-repair-efficiency BISR (HRE-BISR) scheme for RAMs is proposed. The HRE-BISR reuses the local bitmap to serve as spare bits such that it can repair more faults. In addition, a row/column/bit redundancy analysis (RCB-RA) algorithm for a RAM with spare rows, spare columns, and spare bits is presented. Simulation results show that the proposed HRE-BISR scheme can provide higher repair rate (RR) than a typical BISR scheme without reusing the local bitmap as spare bits. Only about 0.44% additional hardware overhead is needed to modify the local bitmap as spare bits. In addition, the HRE-BISR scheme using $3\times 3$ -bit local bitmap for RA only incurs about 0.08-ns delay penalty for a $512\times 16\times 32$ -bit RAM with one spare row and one spare column. However, the HRE-BIRA scheme with RCB-RA algorithm can provide 0.48%–11.95% increment of RR for different fault distributions. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to index color images using the features extracted from the error diffusion block truncation coding (EDBTC). The EDBTC produces two color quantizers and a bitmap image, which are further processed using vector quantization (VQ) to generate the image feature descriptor. Herein two features are introduced, namely, color histogram feature (CHF) and bit pattern histogram feature (BHF), to measure the similarity between a query image and the target image in database. The CHF and BHF are computed from the VQ-indexed color quantizer and VQ-indexed bitmap image, respectively. The distance computed from CHF and BHF can be utilized to measure the similarity between two images. As documented in the experimental result, the proposed indexing method outperforms the former block truncation coding based image indexing and the other existing image retrieval schemes with natural and textural data sets. Thus, the proposed EDBTC is not only examined with good capability for image compression but also offers an effective way to index images for the content-based image retrieval system. [ABSTRACT FROM PUBLISHER]

To render 3-D graphics efficiently, rasterization techniques have been developed. Traditional triangle traversal techniques using scan-line-based or edge-equation-based methods may cause potential instability from the division operations. This paper develops an efficient rasterization algorithm—a barycentric-based ladder start tile traversal that is division free. Throughout the process, no extra traversal position and context is produced to reduce the number of pixel tests and improve the efficiency and stability of the graphic rendering. It also presents the architecture of a 300 MHz 3-D graphics rasterizer in a 65 nm 1P9M process with a core size of 0.537 mm \(^{2}\) and internal buffer 3 K. The proposed ladder start tile traversal architecture can perform each tile intersect test in six cycles and tile interior traversal with barycentric tests in 2 pixels per cycle. In addition, the rasterizer throughput can achieve up to 50M triangles per second and 600M pixels per second. [ABSTRACT FROM PUBLISHER]

Owing to its superior properties, such as fast identification and relatively long interrogating range over barcode systems, Radio Frequency Identification (RFID) technology has promising application prospects in inventory management. This paper studies the problem of complete identification of missing RFID tag, which is important in practice. Time efficiency is the key performance metric of missing tag identification. However, the existing protocols are ineffective in terms of execution time and can hardly satisfy the requirements of real-time applications. In this paper, a Multi-hashing based Missing Tag Identification (MMTI) protocol is proposed, which achieves better time efficiency by improving the utilization of the time frame used for identification. Specifically, the reader recursively sends bitmaps that reflect the current slot occupation state to guide the slot selection of the next hashing process, thereby changing more empty or collision slots to the expected singleton slots. We investigate the optimal parameter settings to maximize the performance of the MMTI protocol. Furthermore, we discuss the case of channel error and propose the countermeasures to make the MMTI workable in the scenarios with imperfect communication channels. Extensive simulation experiments are conducted to evaluate the performance of MMTI, and the results demonstrate that this new protocol significantly outperforms other related protocols reported in the current literature. [ABSTRACT FROM PUBLISHER]

Decision support and knowledge discovery systems often compute aggregate values of interesting attributes by processing a huge amount of data in very large databases and/or warehouses. In particular, iceberg query is a special type of aggregation query that computes aggregate values above a user-provided threshold. Usually, only a small number of results will satisfy the threshold constraint. Yet, the results often carry very important and valuable business insights. Because of the small result set, iceberg queries offer many opportunities for deep query optimization. However, most existing iceberg query processing algorithms do not take advantage of the small-result-set property and rely heavily on the tuple-scan-based approach. This incurs intensive disk accesses and computation, resulting in long processing time especially when data size is large. Bitmap index, which builds one bitmap vector for each attribute value, is gaining popularity in both column-oriented and row-oriented databases in recent years. It occupies less space than the raw data and gives opportunities for more efficient query processing. In this paper, we exploited the property of bitmap index and developed a very effective bitmap pruning strategy for processing iceberg queries. Our index-pruning-based approach eliminates the need of scanning and processing the entire data set (table) and thus speeds up the iceberg query processing significantly. Experiments show that our approach is much more efficient than existing algorithms commonly used in row-oriented and column-oriented databases. [ABSTRACT FROM PUBLISHER]

The encoding of both texture and depth maps of multiview images, captured by a set of spatially correlated cameras, is important for any 3-D visual communication system based on depth-image-based rendering (DIBR). In this paper, we address the problem of efficient bit allocation among texture and depth maps of multiview images. More specifically, suppose we are given a coding tool to encode texture and depth maps at the encoder and a view-synthesis tool to construct intermediate views at the decoder using neighboring encoded texture and depth maps. Our goal is to determine how to best select captured views for encoding and distribute available bits among texture and depth maps of selected coded views, such that the visual distortion of desired constructed views is minimized. First, in order to obtain at the encoder a low complexity estimate of the visual quality of a large number of desired synthesized views, we derive a cubic distortion model based on basic DIBR properties, whose parameters are obtained using only a small number of viewpoint samples. Then, we demonstrate that the optimal selection of coded views and quantization levels for corresponding texture and depth maps is equivalent to the shortest path in a specially constructed 3-D trellis. Finally, we show that, using the assumptions of monotonicity in the predictor's quantization level and distance, suboptimal solutions can be efficiently pruned from the feasible space during solution search. Experiments show that our proposed efficient selection of coded views and quantization levels for corresponding texture and depth maps outperforms an alternative scheme using constant quantization levels for all maps (commonly used in video standard implementations) by up to 1.5 dB. Moreover, the complexity of our scheme can be reduced by at least 80% over the full solution search. [ABSTRACT FROM PUBLISHER]

Due to the complexity of H.264/AVC, it is very challenging to apply this standard to design a conversational video communication system. This problem is addressed in this paper by using region-of-interest (ROI) based bit allocation and computational power allocation schemes. In our system, the ROI is first detected by using the direct frame difference and skin-tone information. Several coding parameters including quantization parameter, candidates for mode decision, the number of referencing frames, accuracy of motion vectors and the search range of motion estimation are adaptively adjusted at the macroblock (MB) level according to the relative importance of each MB. Subsequently, the encoder could allocate more resources such as bits and computational power to the ROI, and the decoding complexity is also optimized at the encoder side by utilizing an ROI based rate-distortion-complexity (R-D-C) cost function. The encoder is thus simplified and decoding-friendly, and the overall subjective visual quality can also be improved. [ABSTRACT FROM AUTHOR]

Integer cosine transform (ICT) is adopted by H.264/AVC for its bit-exact implementation and significant complexity reduction compared to the discrete cosine transform (DCT) with an impact in peak sigal-to-noise ratio (PSNR) of less than 0.02 dB. In this paper, a new technique, named prescaled integer transform (PIT), is proposed. With PIT, while all the merits of ICT are kept, the implementation complexity of decoder is further reduced compared to corresponding conventional ICT, which is especially important and beneficial for implementation on low-end processors. Since not all PIT kernels are good in respect of coding efficiency, design rules that lead to good PIT kernels are considered in this paper. Different types of PIT and their target applications are examined. Both fixed block-size transform and adaptive block-size transform (ABT) schemes of PIT are also studied. Experimental results show that no penalty in performance is observed with PIT when the PIT kernels employed are derived from the design rules. Up to 0.2 dB of improvement in PSNR for all intra frame coding compared to H.264/AVC can be achieved and the subjective quality is also slightly improved when PIT scheme is carefully designed. Using the same concept, a variation of PIT, Post-scaled Integer Transform, can also be potentially designed to simplify the encoder in some special applications. PIT has been adopted in audio video coding standard (AVS), Chinese National Coding standard. [ABSTRACT FROM AUTHOR]

The efficient progressive transmission of a textured 3-D model, which has a texture image mapped on a geometric mesh, requires careful organization of the bit stream to quickly present high-resolution visualization on the user's screen. Bit rates for the mesh and the texture need to be properly balanced so that the decoded model has the best visual fidelity during transmission. This problem is addressed in the paper, and a bit allocation framework is proposed. In particular, the relative importance of the mesh geometry and the texture image on visual fidelity is estimated using a fast quality measure (FQM). Optimal bit distribution between the mesh and the texture is then computed under the criterion of maximizing the quality measured by FQM. Both the quality measure and the bit allocation algorithm are designed with low computation complexity. Empirical studies show that not only the bit allocation framework maximizes the receiving quality of the textured 3-D model, but also it does not require sending additional information to indicate bit boundaries between the mesh and the texture in the multiplexed bit stream, which makes the streaming application more robust to bit errors that may occur randomly during transmission. [ABSTRACT FROM AUTHOR]

In this paper, a novel H.264 multiple description technique is proposed. The coding approach is based on the redundant slice representation option, defined in the H.264 standard. In presence of losses, the redundant representation can be used to replace missing portions of the compressed bit stream, thus yielding a certain degree of error resilience. This paper addresses the creation of two balanced descriptions based on the concept of redundant slices, while keeping full compatibility with the 11.264 standard syntax and decoding behavior in case of single description reception. When two descriptions are available still a standard H.264 decoder can be used, given a simple preprocessing of the received compressed bit streams. An analytical setup is employed in order to optimally select the amount of redundancy to be inserted in each frame, taking into account both the transmission condition and the video decoder error propagation. Experimental results demonstrate that the proposed technique favorably compares with other H.264 multiple description approaches. [ABSTRACT FROM AUTHOR]

Very low bit-rate video coding algorithms using predefined regular-shaped patterns to segment out moving objects at macroblock level have exhibited good potential for improved coding efficiency when embedded in the H.264 standard as an extra mode. Even the best-matched regular-shaped pattern from a predefined codebook cannot approximate the shape of the object well, and there is no guarantee that even a regular-shaped object will have a close match with one of the limited number of predefined patterns. Intuitively, improved coding performance can be achieved if patterns are dynamically extracted from the video content. This letter presents a content-based pattern generation (CPG) algorithm for a set of macroblocks, which is shown optimal when only one pattern is allowed to represent the entire set. Coupling CPG, generating a pattern codebook after clustering the macroblocks into several disjoint sets, with any pattern selection algorithm outperforms the existing regular-shaped pattern-based coding while both embedded in H.264. [ABSTRACT FROM AUTHOR]

We propose a normalization technique for verifying arithmetic circuits in a bounded model-checking environment. Our technique operates on the arithmetic bit-level (ABL) description of the arithmetic circuit parts and property. The ABL description can easily be provided by the front-end of a register transfer level property checker. The proposed normalization greatly simplifies the SAT instances to be solved for arithmetic circuit verification. Our approach has been successfully applied to verify the integer pipeline of an industrial microprocessor with advanced DSP capabilities. [ABSTRACT FROM AUTHOR]

This paper presents a novel rate control scheme for low delay video communication of H.264/AVC standard. A switched mean-absolute-difference (MAD) prediction scheme is introduced to enhance the traditional temporal MAD prediction model, which is not suitable for predicting abrupt MAD fluctuations. Our new model could reduce the MAD prediction error by up to 69%. Furthermore, an accurate linear rate-quantization (R-Q) model is also formulated to describe the relationship between the total amount of bits for both texture and nontexture information and the quantization parameter (QP), so that the negative effect caused by the inaccurate estimation of nontexture bits is removed. By exploring the relationship between peak signal-to-noise ratio and QP value, the proposed linear R-Q model could further optimize QP calculation at the macroblock level. When compared with the rate control scheme JVT-G012 [1] which is adopted by the latest JVT H.264/AVC reference model JM9.8, the proposed rate control algorithm could reduce the mismatch between actual bits and target ones by up to 75%. To meet the low delay requirement, the buffer is better controlled to prevent overflowing and underflowing. The average luminance PSNR of reconstructed video is increased by up to 1.13 dB at low bit rates, and the subjective video quality is also improved. [ABSTRACT FROM AUTHOR]

Variable-bit-rate (VBR) encoded videos can provide a more consistent visual quality than constant-bit-rate (CBR) encoded videos. However, the long-range bit-rate variations in VBR videos make it difficult to efficiently provide quality-of-service control in a video-on-demand system. Existing scheduling algorithms such as Optimal Smoothing, which requires both downward and upward bandwidth reallocations to adapt to the video bit-rate variations, simply cannot guarantee video delivery in networks with mixed video and data traffic. This study tackles this limitation by investigating a new scheduling algorithm with monotonic-decreasing rate allocations for scheduling video data transmissions. By eliminating upward bandwidth reallocations, the proposed scheduler can guarantee video delivery even in the presence of other data traffic in the same network. Moreover, results show that the proposed scheduler can achieve such performance guarantee without tradeoff in performance or resource requirements. This paper presents this new monotonic-decreasing rate scheduler, analyzes its fundamental properties, and evaluates its performance using a large number of real-world VBR video traces (274 DVD movies) in extensive trace-driven simulations. [ABSTRACT FROM AUTHOR]

This paper concerns the problem of selecting a binary labeling for the signal constellation in M-PSK, M-PAM, and M-QAM communication systems. Gray labelings are discussed and the original work by Frank Gray is analyzed. As is noted, the number of distinct Gray labelings that result in different bit-error probability grows rapidly with increasing constellation size. By introducing a recursive Gray labeling construction method called expansion, the paper answers the natural question of what labeling, among all possible constellation labelings, will give the lowest possible average probability of bit errors for the considered constellations. Under certain assumptions on the channel, the answer is that the labeling proposed by Gray, the binary reflected Gray code, is the optimal labeling for all three constellations, which has, surprisingly, never been proved before. [ABSTRACT FROM AUTHOR]

A rigorous derivation is given of the coding rate of a variable-to-variable length bit-stuffing coder for a two-dimensional (1, ∞) -constrained channel. The coder studied is "nearly" a fixed-to-fixed length algorithm. Then an analogous variable-to-variable length bit-stuffing algorithm for the three-dimensional (1, ∞) -constrained channel is presented, and its coding rate is analyzed using the two-dimensional method. The three-dimensional coding rate is demonstrated to be at least 0.502, which is proven to be within 4% of the capacity. [ABSTRACT FROM AUTHOR]

This paper describes the proposed improvements to the ATSC DTV standard The proposed system provides a mechanism for embedding a new robust bit-stream in the standard bit-stream in a backward compatible manner. The robust stream has a higher threshold of visibility (TO V) compared to the standard stream and can be transmitted either in the pseudo 2-VSB mode or in the enhanced-coded 8-VSB (E-VSB) mode. A prototype transceiver system, based on the proposed system, has been developed and was tested in the lab and in the field. The results of these tests will be briefly reviewed in this paper. [ABSTRACT FROM AUTHOR]

A novel network-assisted (signal processing based) medium access control (MAC) protocol known as the bit-map-assisted dynamic queue (BMDQ) is presented in this paper. The protocol is explicitly designed for a wireless slotted system with multiple packet reception (MPR) capability. In the proposed protocol, the traffic in the channel is viewed as a flow of transmission periods (TPs). Each TP has a bit-map (BM) slot at the beginning followed by a data transmission period (DP). The BM slot is reserved for user detection so that accurate knowledge of active user set (AUS) can be obtained. Then, given the knowledge of the AUS and the channel MPR matrix, the number of users that can access the channel simultaneously in each packet slot in the DP is chosen to maximize the conditional throughput of every packet slot. Compared with other conventional and network-assisted MAC protocols, the proposed BMDQ protocol yields better performance. Its maximum steady-state throughput is close to the channel MPR capacity, and it can achieve the same throughput with lower traffic load and smaller delay. Performance issues are investigated analytically and via simulations. [ABSTRACT FROM AUTHOR]

Comments on the watermarking scheme proposed by Hwang, Chang and Hwang (HCH). Description of the HCH-watermarking scheme; Information on the bit-complement attack; Experimental results on attacking the HCH-watermarking scheme.

The article discusses the cover image of the publication "IEEE Computer Graphics and Applications" in the July/August 2006 issue. The cover image was digitally designed by Ukraine-based graphic artist Valeriy Grachov. Grachov stressed that on designing the image, he wanted a reproduction of the flickering cobwebs which consisted of thin twigs and depicted as being immersed in the sunset. He accounted that the said concept was his most complicated task he had ever done. He used both features of Corel Painter and Adobe Photoshop.