Efficient Motion Estimation Research Articles

Region similarity based edge detection for motion estimation in H.264/AVC

This paper introduces a block-based motion estimation algorithm based on projection with adaptive window size selection. By using one-dimensional (1-D) projection the original two-dimensional (2-D) block-matching problem is translated to a simpler 1D matching, which eliminates majority of potential pixel participation. In this paper, we propose an efficient fast motion estimation method by using region similarity detection (RSD) algorithm to reduce the encoding time. The proposed RSD algorithm effectively estimates the texture direction of the block to find the direction and then horizontal, vertical or diagonal projection is employed for SAD calculation. Experimental results show that the proposed algorithm achieves more than a 60% time reduction with negligible PSNR loss and bitrate increments.

An Analog Processor Array Implementing Interconnect-Efficient Reference Data Shift and SAD/SSD Extraction for Motion Estimation

A cellular analog processor array for use in variable block-size motion estimation with a new simple method for shifting reference image data is presented. The new shift method leads to a greatly reduced number of neighborhood connections for each cell of the array, and allows for all shifts within the [8,8] search area to be performed in a single step, with simple digital controls. The new shift circuitry, together with some other cell and system level optimizations, reduces silicon area and array layout complexity, enabling faster and more efficient parallel full search motion estimation hardware. A 32 × 32 cell parallel analog test array for reference-shift with a maximum block-size of 16 × 16, as well as absolute value/quadratic processing for variable block-size analog motion estimation (AME) has been designed in a 0.13 µm CMOS technology.

Predictive cross-hexagon search algorithm for fast block motion estimation

Block-matching motion estimation plays an important role in real-time video compression and thus has significant impact on searching speed and quality of performance. In order to address these issues, we introduce a highly efficient block motion estimation algorithm, referred to as a predictive cross-hexagon search (PCHS) algorithm, that can considerably reduce the complexity of the Joint Video Team (JVT) encoder. In contrast to many classical fast motion estimation algorithms, PCHS has three desirable features: (1) prediction of a search center, (2) usage of search patterns with different sizes, and (3) early algorithm termination that makes it adaptive and effective. We set four predictor candidates for initial search point options and then increase the accuracy of the predictor. The different-size search patterns, including small cross search patterns, hexagon search patterns, and cross-hexagon search patterns, used in the searching process can better suit more motion types. Due to the high accuracy of the predictor, the proposed algorithm adapts early termination; as the predictor is good enough, the search stops early. Therefore, the PCHS algorithm is suitable for real-time video encoding, as it can speed up the encoder without sacrificing performance compared with other fast algorithms.

Efficient Hierarchical Motion Estimation Algorithm and Its VLSI Architecture

This paper addresses the development and hardware implementation of an efficient hierarchical motion estimation algorithm, HMEA, using multiresolution frames to reduce the computational complexity. Excellent estimation performance is ensured using an averaging filter to downsample the original image. At the smallest resolution, the least two motion vector candidates are selected using a full-search block matching algorithm. At the middle level, these two candidate motion vectors are employed as the center points for small range local searches. Then, at the original resolution, the final motion vector is obtained by performing a local search around the single candidate from the middle level. HMEA exhibits regular data flow and is suitable for hardware implementation. An efficient VLSI architecture that includes an averaging filter to downsample the image and two 2-D semisystolic processing element arrays to determine the sum of absolute difference in pipeline is also presented. Simulation results indicate that HMEA is more area-efficient and faster than many full-search and multiresolution architectures while maintaining high video quality. This architecture with 59K gates and 1393 bytes of RAM is implemented for a search range of [ -16.0, +15.5].

Towards an H.264/AVC HW/SW Integrated Solution: An Efficient VBSME Architecture

This paper presents an efficient real-time variable block size motion estimation architecture. The proposed architecture provides motion vectors for each 16 times 16 block and its 40 sub-blocks. The proposed architecture is a single-instruction multiple-data architecture integrated with embedded SRAMs on one chip. The architecture has been prototyped using Xilinx Virtex-4 XC4VSX35-10 field-programmable gate array. It processes 30-CIF fps using 71-MHz clock frequency. Its maximum clock frequencyuency is 187.7 MHz and the maximum throughput is 20 4CIF fps. The prototyped architecture has 175 k gates and 18 kbits embedded SRAM.

Reducing the complexity of MPEG-4 global motion estimation using pixel subsampling

MPEG-4 uses a perspective model for global motion estimation. The region of support for global motion representation consists of the entire image frame. Estimating global motion parameters is very expensive computationally, since all the pixels in the frames are involved in the computation. Therefore, computationally efficient global motion estimation techniques are sought-after. It is shown that real-time global motion estimation in an MPEG-4 video codec can be achieved by using a pixel subsampling method based on regular subsampling patterns. Simulation results demonstrated that the proposed method was capable of speeding up the conventional all-pixel GME approach by more than 11 times, with a subsampling ratio of 1/16, without significant loss in estimation accuracy and compression efficiency.

세분화된 탐색 범위에서의 방향 지향적 전영역 고속 탐색 알고리즘

본 논문에서는 비디오 부호화의 움직임 예측에 사용되는 블록 정합 알고리즘의 계산량을 줄이는 고속 전영역 탐색 알고리즘을 제안한다. 블록 정합 알고리즘에서 사용되는 기존의 나선형 탐색 알고리즘은 탐색 영역의 중심에서 시작하여 탐색 지점을 화소 단위로 이동화면서 움직임 예측을 수행하기 때문에 움직임이 적은 영상에 적합하다. 본 논문에서는 움직임이 작은 영상 뿐 아니라 움직임이 많은 영상에서도 효율적인 움직임 예측을 하기 위해 다음과 같은 알고리즘을 제안한다. 먼저 초기 문턱 값을 계산함에 있어서 확장된 예측기를 사용하여 보다 최소값에 근사한 문턱값을 계산한다. 그리고 탐색영역을 블록으로 세분화 한 후 각 영역을 새로운 탐색 순서에 따라 움직임 예측을 수행하고 방향성에 따라 영역을 재분할한다. 재분할된 영역이 가지는 방향성에 따라 방향 지향적인 탐색 순서를 적용한다. 실험 결과에서 제안하는 알고리즘이 기존의 나선형 전영역 탐색 알고리즘에 비해 객관적인 화질의 열화 없이 계산량이 평균적으로 약 94% 감소하는 것을 확인할 수 있다. We propose the fast full search algorithm that reduces the computational load of the block matching algorithm which is used for a motion estimation in the video coding. Since the conventional spiral search method starts searching at the center of the search window and then moves search point to estimate the motion vector pixel by pixel, it is good for the slow motion picture. However we proposed the efficient motion estimation method which is good for the fast and slow motion picture. Firstly, when finding the initial threshold value, we use the expanded predictor that can approximately calculate minimum threshold value. The proposed algorithm estimates the motion in the new search order after partitioning the search window and adapt the directional search order in the re-divided search window. At the result, we can check that the proposed algorithm reduces the computational load 94% in average compared to the conventional spiral full search algorithm without any loss of image quality.

An Efficient Binary Motion Estimation Algorithm and its Architecture for MPEG-4 Shape Encoding

This paper presents a fast binary motion estimation (BME) algorithm and its architecture for MPEG-4 shape encoding. The proposed algorithm explores the property of the binary-value in BME to quickly skip the unnecessary sum of absolute differences (SAD) computation. When comparing with the full search algorithm, simulation results show that it can efficiently save in the search positions to an average <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-hbox99.58$</tex> % of that in the full search algorithm with the same PSNR quality. Due to the algorithm's simplicity and regularity, the resulting hardware implementation also exhibits simple and regular control and data flow. It can achieve real-time encoding with only 11582 gate count.

Efficient wavelet-domain motion estimation scheme for wavelet-based video coding

Motion estimation is a key element of the video coder, which heavily affects the performance of video coding. However, the most significant problem of the discrete wavelet transform is the shift-variant property, which makes the wavelet-domain motion estimation inaccurate. To eliminate the influence of shift variance, an optimal synthesis filtering method is introduced and an efficient motion estimation scheme using the proposed method is presented, which can perform the motion estimation accurately. The experiment results show that the proposed motion estimation scheme outperforms the other wavelet-domain motion estimation schemes by 0.7 dB and has moderate complexity.

Scalable VLSI Architecture for Variable Block Size Integer Motion Estimation in H.264/AVC

Because of the data correlation in the motion estimation (ME) algorithm of H.264/AVC reference software, it is difficult to implement an efficient ME hardware architecture. In order to make parallel processing feasible, four modified hardware friendly ME workflows are proposed in this paper. Based on these workflows, a scalable full search ME architecture is presented, which has following characteristics: (1) The sum of absolute differences (SAD) results of 4 × 4 sub-blocks is accumulated and reused to calculate SADs of bigger sub-blocks. (2) The number of PE groups is configurable. For a search range of M × N pixels, where M is width and N is height, up to M PE groups can be configured to work in parallel with a peak processing speed of N × 16 clock cycles to fulfill a full search variable block size ME (VBSME). (3) Only conventional single port SRAM is required, which makes this architecture suitable for standard-cell-based implementation. A design with 8 PE groups has been realized with TSMC 0.18 μm CMOS technology. The core area is 2.13 mm × 1.60 mm and clock frequency is 228 MHz in typical condition (1.8 V, 25°C).

Efficient block-matching motion estimation based on Integral frame attributes

Block-based motion estimation is widely used in video compression for exploiting video temporal redundancy. Although effective, the process is arguably the most computationally intensive part of a typical video encoder. To speed up the process, a large number of fast block-matching algorithms (BMAs) have been proposed for motion estimation by limiting the number of search locations or simplifying the measure of match between the two blocks under comparison. In this paper we propose a new BMA that measures the match by using such features as block sum and block variance, which can be easily computed using integral frame attributes. Experimental results show that the proposed BMA can reduce the computational complexity notably and achieve compression performance very close to that of existing BMAs using conventional block-matching measures.

A variable block size motion estimation algorithm for real-time H.264 video encoding

This paper presents an efficient variable block size motion estimation algorithm for use in real-time H.264 video encoder implementation. In this recursive motion estimation algorithm, results of variable block size modes and motion vectors previously obtained for neighboring macroblocks are used in determining the best mode and motion vectors for encoding the current macroblock. Considering only a limited number of well chosen candidates helps reduce the computational complexity drastically. An additional fine search stage to refine the initially selected motion vector enhances the motion estimator accuracy and SNR performance to a value close to that of full search algorithm. The proposed methods result in over 80% reduction in the encoding time over full search reference implementation and around 55% improvement in the encoding time over the fast motion estimation algorithm (FME) of the reference implementation. The average SNR and compression performance do not show significant difference from the reference implementation. Results based on a number of video sequences are presented to demonstrate the advantage of using the proposed motion estimation technique.

Stereoscopic video generation based on efficient layered structure and motion estimation from a monoscopic image sequence

This paper presents a novel object-based method for the generation of a stereoscopic image sequence from a monoscopic video, using bidirectional two-dimensional motion estimation for the recovery of rigid motion and structure and a Bayesian framework to handle occlusions. The latter is based on extended Kalman filters and an efficient method for reliably tracking object masks. Experimental results show that the layered object scene representation, combined with the proposed algorithm for reliably tracking object masks throughout the sequence, yields very accurate results.

A model-based adaptive motion estimation scheme using Renyi’s entropy for wireless video

Efficient motion estimation is an important problem because it determines the compression efficiency and complexity of a video encoder. Motion estimation can be formulated as an optimization problem; most motion estimation algorithms use mean squared error, sum of absolute differences or maximum a posteriori probability as the optimization criterion and apply search-based techniques (e.g., exhaustive search or three-step search) to find the optimum motion vector. However, most of these algorithms do not effectively utilize the knowledge gained in the search process for future search efforts and hence are computationally inefficient. This paper addresses this inefficiency problem by introducing an adaptive motion estimation scheme that substantially reduces computational complexity while yet providing comparable compression efficiency, as compared to existing fast-search methods. Our approach is motivated by the recent developments in using Renyi’s entropy as the optimization criterion for system modeling [D. Erdogmus, J. Principe, Comparison of entropy and mean square error criteria in adaptive system training using higher order, in: Proceedings of the International Workshop on Independent Component Analysis and Signal Separation, Helsinki, Finland, 2000, pp. 75–80]. This scheme is particularly suited for wireless video sensor networks, video conferencing systems and live streaming videos which have stringent computational requirements. Our results show that our scheme reduces the computational complexity by a factor of 9–21, compared to the existing fast algorithms.

Similarity motion estimation and active tracking through spatial-domain projections on log-polar images

To cope with the huge amount of visual data in the environment, foveal sensing is not only an elegant biological solution, but also an appropriate mechanism in computer-based vision of artificial agents such as robots. An extremely important visual behavior in active vision systems is that of actively tracking moving targets, which is a problem closely related with foveal vision. The work described in this article has precisely to do with active tracking with space-variant images. The two main components of the proposed algorithm are the log-polar image format, and a projection-based motion estimator, whose joint use results in an efficient and effective active tracking scheme. For the successful real-time performance of the proposed approach, it is very important to have an appropriate combination of: (i) an efficient motion estimation technique, (ii) an adequate image representation, and (iii) the dynamic nature of purposive vision.

A simple and efficient block motion estimation algorithm based on full-search array architecture

This paper first presents an array structure using ± 1 full-search (FS) architecture as the search engine of block motion estimation which takes advantage of the design regularity of FS. An efficient algorithm named modified gradient-descent search (MGDS) is then introduced based on the proposed architecture. MGDS utilizes an adaptive computation distribution mechanism to efficiently allocate computation of the employed ± 1 FS array to blocks or frames of video sequences. Experimental results indicate that MGDS uniformly achieves a higher quality than FS by an amount that is dependent on motion activities of sequences.

Automatic feature-based global motion estimation in video sequences

In this paper, automatic and efficient global motion estimation for video sequences is proposed. In this estimation, we find and pick up pairs of feature points in the edge lines within the successive frames using the match algorithm. We then choose the best set of three pair points to measure the parameters of the Affine Model which describes the global motion. The result shows that we can obtain the Affine parameters of global motion efficiently in video sequences.

Scalable video compression via overcomplete motion compensated wavelet coding

Recently, there have been a flurry of works on overcomplete motion compensated wavelet coding (OMCWC). In this paper, we address the importance of phase and focus on the design of scalable video coding algorithms within the OMCWC framework. Specifically, our new contributions consist of the following three components: (1) efficient block motion estimation techniques in the wavelet domain including hierarchical and fractional-pel block matching, (2) extend overcomplete motion compensated prediction (MCP) into overcomplete motion compensated temporal filtering (MCTF) to achieve temporal scalability (3) context modeling strategies for embedded quantization and entropy coding of 3D wavelet coefficients. Experiment results are used to demonstrate that the class of overomplete MCP/MCTF coders are capable of achieving comparable performance to other competing interframe wavelet coders.

Predictive line search: an efficient motion estimation algorithm for MPEG-4 encoding systems on multimedia processors

This paper describes an efficient motion estimation algorithm, the predictive line search (PLS), for real-time implementations of MPEG-4 encoder on multimedia processors. The motion-vector predictor is used as the starting point in the search process because the correlation between neighboring motion vectors is strong. The line search pattern is used in the proposed algorithm to reduce the memory access as well as to exploit the special multimedia processor instructions for sum of absolute difference calculations. Experimental results show that the performance of the PLS is very close to that of the full-search (FS) algorithm. Compared with the well-known diamond search and one-dimensional FS, the PLS shows better performance and robustness, especially for high motion sequences. A prototype MPEG-4 encoding system is implemented on a 216-MHz multimedia processor with very long instruction word architecture to verify the effectiveness of the PLS. Real-time encoding of MPEG-4 Simple Profile Level 3 (CIF, 30 fps) can be achieved with only 57% of the processor load.

An analysis and efficient implementation of half-pel motion estimation

Subpixel motion compensation has become a main ingredient in many modern video compression standards due to its ability to provide accurate motion prediction. To obtain fine motion vector accuracy, video encoders incorporate a motion estimation process at the subpixel level. This process is generally limited to a small area around the integer pixel motion vector in order to keep complexity small. This paper proposes an efficient motion estimation method for video encoders to generate 8/spl times/8 half-pel motion vectors. By reusing the matching costs from a previous motion estimation task, the proposed method selectively ignores redundant candidate vectors that have already been searched, thereby reducing complexity without sacrificing search quality. An analysis of the redundancy is presented and simulation results are reported which show promising reductions in the number of 8/spl times/8 search point positions. Although this paper focuses on a specific problem of half-pel motion estimation for 8/spl times/8 blocks, the approach can be generalized for efficient motion estimation for other block sizes, pixel resolutions and search ranges.