nils-herrmann/clean_scirepeval huggingface dataset:
Depth Sensation Enhancement for Multiple Virtual View Rendering

Depth information is an indispensable element in depth image-based rendering (DIBR) for three-dimensional (3-D) display. In this paper, we propose a novel depth sensation enhancement method to address the problems in multiple virtual view rendering. First, as the depth sensation is decreased when rendering intermediate multiple virtual views, the basic principle of depth sensation enhancement is derived according to the number of rendering views. Second, with the increase of the scene complexity, it is difficult to ensure the depth sensation of all neighboring objects. The saliency analysis is adopted to give preferred guarantee to the depth sensation between the salient object and its neighbors. Then, the depth sensation enhancement for multiple virtual view rendering is performed based on a defined energy function built by the number of rendering views and the saliency analysis. Finally, considering the temporal consistency between adjacent frames, the depth sensation enhancement is extended to video applications with a newly designed energy function with energy term of temporal consistency preservation. Experimental results on a public database demonstrate that the proposed method can obtain promising performance in depth sensation.
Frame-layer H.264 rate control improvement using Lagrange multiplier and quantizer

The paper presents a frame-layer rate control for H.264 that computes the Lagrange multiplier (/spl lambda//sub MODE/) for mode decision by using a quantization parameter (QP) which may be different from that used for encoding. At the same time, we also compare the bits produced by each mode with the average target bits of each macroblock (MB) in a frame to modify /spl lambda//sub MODE/ further. The objective of these measures is to produce bits as close to the frame target bits as possible. In order to obtain an accurate QP for a frame, we employ a complexity-based bit allocation scheme and a QP adjustment method. Simulation results show that the H.264 encoder, using the proposed algorithm, controls the bit rate better, achieves a visual quality improvement of about 0.5 dB better than that of the existing H.264 rate control method (JVT-G012), with a smaller visual quality variation.
Bit rate distribution for motion estimation in H.264 coding

In this paper, we analyze the bit rate distribution of the full search and the fast search motion estimation algorithms in H.264. It shows both experimentally and theoretically that a well-designed fast block-matching algorithm not only speeds up motion estimation process, but also improves the rate-distortion performance. This is in contrast to the common belief that full search always yields optimal rate-distortion performance under the same test condition.
Bit Allocation Scheme for Low-Delay H.264/AVC Rate Control

This paper presents an efficient rate control scheme for H.264/AVC video coding in low-delay environments. In our scheme, we propose a close-form solution to optimal bit allocation problem subject to constraints and we derive theoretically a mean absolute difference based (MAD-based) complexity measure. The complexity measure of the current macroblock is also used to predict SKIP mode such that the initial quantization parameter (QP) is determined directly. Initial QPs of other kind of macroblocks (MBs) are computed based on a conventional quadratic model. To prevent the buffer from undesirable overflow or underflow under small buffer size constraint, the obtained initial QP is further adjusted based on actual encoding results at that point. Simulation results show that the H.264 encoder, using our proposed scheme, achieves a visual quality improvement of about 0.65 dB on the average and performs better for buffer overflow and underflow.
Comparisons of different systolic arrays for the QR decomposition based least squares technique

Systolic arrays are very useful for implementing complex signal processing algorithms particularly for real-time and high bandwidth requirements. For example, the two systolic array implementations developed by Gentleman and Kung (1981) and McWhirter (1983) are two-dimensional arrays of processing elements. The QR decomposition-based least-squares method for linear prediction has been applied to the problem of computing the reflection coefficients of a lattice predictor, instead of using the conventional Burg algorithm. A modified one-dimensional ring architecture was proposed for implementing the QR algorithm. This means that the QR algorithm can now be implemented on a linear one-dimensional array of processors rather than a 2-dimensional array as is customary. This 1-D linear array was obtained by a mapping technique. There are other one-dimensional (linear) arrays derived algorithmically or by mapping methods for solving the same problem. In this paper, we specify the details of the cells of our new one-dimensional linear array and then compare this array with the other possible linear arrays for solving the same and QR decomposition least-squares problem.
Optimized nested protection for video Region of Interest with Raptor codes

Due to the best effort feature of many existing transmission channels, video streams often suffer from inevitable transmission errors. In this paper, we propose a scheme of robust video transmission based on the state-of-the-art Raptor codes, whose applications are in full swing now. And considering Region of Interest (ROI) often draws much attention in images, the scheme adopts a nested protection framework to show partialities to ROI areas for better protection. Different from many existing Raptor codes based UEP methods, our scheme is developed based on the easy-to-use standardized Raptor codes. Experimental results show that significant robustness can be obtained for the video streams, especially for the ROI areas.
Stereoscopic Image Stitching Based on a Hybrid Warping Model

Traditional image editing techniques cannot be directly used to process stereoscopic media, as extra constraints are required to ensure consistent changes between the left and right images. In this paper, we propose a hybrid warping model for stereoscopic image stitching by combining projective and content-preserving warping. First, a uniform homography algorithm is proposed to prewarp the left and right images, and thus ensure consistent changes. Second, a content-preserving warping is introduced to locally refine alignment and reduce vertical disparities. Finally, a seam-cutting-based algorithm is used to find a blending seam, and the multiband blending algorithm is used to produce the final stitched image. Experimental results show that the proposed method can effectively stitch stereoscopic images, which not only avoids local distortions, but also reduces vertical disparities reasonably.
Prediction-based adaptive transform coefficients scanning for inter-frame video coding

In H.264/MPEG-4 AVC, the quantized coefficients are typically scanned in a fixed zig-zag pattern. This fixed scanning order may not always be optimal for entropy coding. To achieve better entropy coding gain in inter-frame coding, we propose a predictive scan ordering scheme and show that additional inter-frame coding redundancy can be removed by our proposed method. The scanning orders are dynamically updated based on the probabilistic distribution of quantized coefficients in the previous frames. Extensive experimental results demonstrate that the proposed algorithm improves coding efficiency by an average of 3.62% and up to 5.63% with negligible additional computational cost.
Two-dimensional multirate systolic array design for artificial neural networks

In this paper a novel design of neural networks using 2-dimensional systolic array is proposed. Two techniques are applied in the design, namely, 2-dimensional pipelining and multirate processing (2 level clocking). 2-dimensional pipelining operation gives significant improvement in computation time compared to the currently known 1D and 2D systolic implementation schemes. Besides, multirate clocking is used so that weights (synapses) can be transmitted and passed systolically in a rate much higher than activation voltages, to achieve maximum array throughput and to eliminate global interconnections present in many array (including systolic) designs (thus reducing synchronization and propagation delay problems). This scheme of passing weights also saves area significantly since local storage area for the weights can be reduced. The design is applied to the implementation of a Hopfield neural net.<<ETX>>
On enhancing H.264 rate control by PSNR-based frame complexity estimation

This work presents an enhancement to the frame layer buffer status-based H.264 rate control method. The enhancement is by using a PSNR-based frame complexity estimation to improve the existing mean absolute difference based (MAD-based) complexity measure. Bit allocation to each frame is not just computed by encoder buffer status but also adjusted by a combined frame complexity measure. Simulation results show that the H.264 encoder, using the proposed algorithm, can achieve better visual performance than that of the existing H.264 JVT rate control method (JVT/spl I.bar/G012).
On over-exposed region detection with regularized logistic regression

Over-exposed region detection is commonly used for image editing and other applications such as over-exposure corrections. In broadcasting, over-exposed regions in image/video can be detected and corrected prior to sending them to consumers. However, the current detection of over-exposed regions is sometimes inaccurate. The detected over-exposed regions are susceptible to noise and scattered. In this paper, we proposed detecting over-exposed regions in images using L2 regularized logistic regression (LR). Over-exposed regions are accurately detected using several novel features in the LR model. These include modeling the characteristics of over-exposed regions as clusters rather than isolated pixels. In addition, overexposed regions are also characterized by both intensity and chrominance pixel values. Optimal parameters for the classifier are obtained by performing training on different scenes. The experimental results show that the detected over-exposed regions are more spatially connected and perceptually accurate compared with current techniques with comparable fast processing.
Optimizing facial animation parameters for MPEG-4

This paper presents a method for automatic optimization of FAPs (facial animation parameters) based on a face video sequence. An FAP optimizer unit compares a rendered face with the original face in the video sequence. The difference is iteratively minimized to produce an optimal set of FAPs. Unnecessary FAPs are eliminated and the search is partitioned to speed up the optimization process. Three different search techniques, steepest descent method, linear search method, and cyclic coordinates method are applied to derive an optimum. The FAPs are very accurate and the animation based on the FAPs is lifelike and truthful to the original video.
Chroma Coding Efficiency Improvement with Context Adaptive Lagrange Multiplier (CALM)

The increasing interest in higher fidelity video initiated the need of higher efficient coding. Color pictures are usually compressed in a luma-chroma coordinate space. One of the important components in H.264 encoding is to find optimal motion vectors and modes to minimize both luma and chroma coefficients bits. This paper proposes a new simple and efficient method to adjust Lagrange multipliers based on the context (context adaptive Lagrange multiplier or CALM), which improves the accuracy for the detection of true motion vectors as well as the most efficient encoding modes for luma which are used for deriving the motion vectors and modes for chroma. Simulation results show that the chroma bit rates can be reduced by 4.36% and 4.80% for U and V components respectively when compared with that of the JM reference software (version 10.2). In addition, the coding efficiency improvement is comparable to the more complicated rate-distortion optimized (RDO) mode decision techniques.
Improved Normalized Partial Distortion Search With Dual-Halfway-Stop for Rapid Block Motion Estimation

Motion estimation is a critical yet computationally intensive task for video encoding. In this paper, we present an enhancement over a normalized partial distortion search (NPDS) algorithm to further reduce block matching motion estimation complexity while retaining video fidelity. The novelty of our algorithm is that, in addition to the halfway-stop technique in NPDS, a dual-halfway-stop (DHS) method, which is based on a dynamic threshold, is proposed, so that block matching is not performed against all matching candidates. An adaptive search range (ASR) mechanism based on inter block distortion further constrains the searching process. Simulation results show that the proposed algorithm has a remarkable computational speedup when compared to that of full search and NPDS algorithms. Particularly, it requires less computation by 92-99% and encounters an average of only 0.08 dB PSNR video degradation when compared to that of full search. The speedup is also very significant when compared to that of fast motion estimation algorithms. This paper describes our work that led to our joint video team (JVT) adopted contribution (included in software JM 10.1 onwards) as well as later enhancements, collectively known as simplified and unified multi-hexagon search (SUMH), a simplified fast motion estimation.
Prediction-based macroblock mode mapping for video coding

This paper describes an efficient entropy coding method for macroblock modes in H.264 based on the statistical information of the previous frame. H.264/MPEG-4 AVC video coding introduces some new macroblock sub-types (modes) that allow for better rate-distortion (R-D) coding. These modes are coded with a fixed mapping table when context adaptive variable length coding (CAVLC) is used. Based on our experiments on the sequences recommended by the Video Coding Experts Group (VCEG) common test conditions, the average number of bits to code those modes is 15% of that of the total bits for coding P-frames. The proposed method maps the more frequently used modes to shorter codeword instead of using a fixed mapping table, and reduces about 10–20% of the bits used for coding the inter modes. This method can be applied to other syntax elements, e.g. coded block pattern (CBP), as well.
On the Coding Efficiency of MCTF Update Steps for Scalable Video Coding

It has been widely believed that motion-compensated update steps performed in the motion-compensated temporal filtering (MCTF) framework improve coding efficiency in comparison to conventional hybrid coding. However, the coding efficiency of MCTF update steps for scalable video coding has not been examined sufficiently in the past. In this paper, we investigate the efficiency of the decoder side update steps by analyzing the effect of performing the inverse update steps at the decoder side. We demonstrate, by theoretical approach, that the MCTF update step at the decoder side does not contribute significantly to the coding efficiency, except at high spatial-temporal resolutions with high bit rates. The results in our study provide a theoretical justification for not including MCTF update steps in the decoding process for scalable video coding
Adaptive transform size and frame-field selection for efficient VC-1 to H.264 high profile transcoding

In this paper, we present a novel technique to transcode VC-1 to H.264 high profile (HP). We use the low frequency AC coefficients to estimate the homogeneity of the block to predict the block transform size and use the magnitude of the motion vectors to help decide transcoding mode for interlaced video. We also analyze the drift error specific to transcoding VC-1 to H.264 and apply this study results to improve final video quality. Implementation of the solution shows that the complexity of the transcoder, when compared to a full-cascaded transcoder, is greatly reduced without a significant loss in peak-signal-to-noise ratio (PSNR).
Fast Depth Modeling Mode selection for 3D HEVC depth intra coding

This paper proposes a fast mode decision algorithm for 3D High Efficiency Video Coding (3D-HEVC) depth intra coding. In the current 3D-HEVC design, it is observed that for most the cases, Depth Modeling Modes (DMM) full-RD search could be skipped since the coding units (CUs) of depth map are usually very flat or smooth and DMMs are designed for CUs with edge or sharp transition. Using Most Probable Mode (MPM) as the indicator, we propose a fast DMM selection algorithm to speed up the encoding process. The test result for the proposed fast algorithm reports 27.8% encoding time saving with 0.31% bitrate increasing in coded and synthesized view for All-Intra test case.
An Iterative Method for Frame-Level Adaptive Wiener Interpolation Filters in Video Coding

In this paper we present an iterative method for improving frame-level adaptive Wiener filtering in video coding. Our method iteratively computes Wiener filter coefficients using the motion field, macroblock partitioning and best coding modes, which are in turn updated in the motion estimation and compensation process using the computed filters. To control the computational complexity of the iterative method, we also propose a termination condition using the mean Euclidean distance of the filter coefficients between consecutive iterations. With extensive computer simulations, we found that our proposed iterative Wiener filtering method produces significant bit rate saving (3.4% on the average) while maintaining the same level of peak-signal-to-noise-ratio (PSNR), compared to the JM 10.1 reference software for H.264/AVC. Most of the performance gain comes from a few iterations at the very beginning. As the number of iteration increases, the further bit rate reduction is less than 1%. Therefore, to achieve the best balance between computational complexity and performance gain, we believe computing Wiener filter coefficients using just 2-3 iterations will suffice
Fast bi-partition mode selection for 3D HEVC depth intra coding

This paper proposes a fast mode decision algorithm for 3D High Efficiency Video Coding (3D-HEVC) depth intra coding. In the current 3D-HEVC design, it is observed that for most of the cases, full Rate-Distortion (RD) cost search of Bi-partition mode could be skipped since most coding units (CUs) of depth map are very flat or smooth while Bi-partition modes are designed for CUs with edge or sharp transition. Using the rough RD cost value calculated by HEVC Rough Mode Decision as a selection threshold, we propose a fast Bi-partition modes selection algorithm to speed up the encoding process. The test result for the proposed fast algorithm reports 34.4% encoding time saving with 0.3% bitrate increasing on synthesized view for All-Intra test case. Moreover, by simply varying the selection threshold, we can make a tradeoff between encoding time saving and bitrate loss based on the requirement of different applications.
A codebook design technique for better image quality in vector quantization

In VQ design, large codebooks are required for better image quality, while less codebook search and memory are desired for better computational efficiency and compression ratio. In this paper, we present an approach to increase the amount of VQ codebook patterns to improve image quality without a large overhead on the codebook memory and search time. Basically, our approach characterizes a pattern into a key value, which is used in codebook search.
Simplified search algorithm for explicit wedgelet signalization mode in 3D-HEVC

As the latest 3D video coding standard, 3D High Efficiency Video Coding (3D-HEVC) achieves efficient coding. Depth coding plays an important role in 3D-HEVC. For better prediction of edges in depth maps, new depth intra modes were proposed, such as Depth Modeling Modes (DMMs). DMM Mode 1, namely explicit wedgelet signalization mode, can improve the performance of synthesized views, but leads to unaffordable encoding computation complexity. In this paper, a simplified search algorithm for explicit wedgelet signalization mode is proposed to predigest the complex search process. First, the proposed algorithm only searches the partition patterns in a limited set based on edge detection in the coarse search stage, since the separation line in the best matching pattern should be similar to the edge in an actual depth prediction unit (PU). Then, a wide range of refinement is implemented to guarantee the coding performance. In fact, up to 24 refinements are tested to provide accurate prediction in the refinement process. Experimental results show that considerable encoding time saving is achieved with negligible performance loss. For all intra test cases, the proposed algorithm achieves an average encoding time saving of 75% for DMM Mode 1 with negligible bitrate increase on synthesized views, compared with the default coarse-refinement algorithm in HTM.
Architecture of a fast motion estimator for MPEG video coding

This paper describes the design of a high speed motion estimator using the 2-D log search algorithm. The architecture consists of 5 simple processing elements (PE) where each PE is capable of computing the sum-of-absolute-difference (SAD) to exploit the parallelism. For each step in the 2-D log search procedure, the 5 SADs of the 5 search points are computed in parallel. The design is implemented using Verilog and synthesized using Synopsys. Such a chip would be able to generate the motion vector for each 16*16 macroblock in 14.58 /spl mu/s for 3-step log search, and 24.30 /spl mu/s for 5-step log search. The architecture is well suited for encoding MPEG2 video up to MP@ML.
An efficient controller scheme for MPEG-2 video decoder

A video decoder with an efficient block-level-pipeline controller scheme for MPEG-2 MP@ML is presented. The architecture in most of the reported literature for MPEG-2 MP@ML video uses a 64-bit bus and a complex bus arbitration scheme to communicate with the external DRAM, the display, and the incoming FIFO. Our design imposes a certain order in the DRAM access by various processing units instead of allowing any processing unit within the decoder to request bus access arbitrarily. This efficient DRAM accessing order allows us to reduce bus width from 64 bits to 32 bits, without significantly increasing the embedded buffer sizes, and still meet the requirements for MPEG-2 MP@ML real-time decoding. The bus arbitration algorithm is also simple, allowing for a less complex controller design.