A new Orthogonal - Diamond Search algorithm for Motion Estimation

In recent years, many fast Block Matching Algorithm or known as BMA have been proposed and developed in order to reduce the computational cost while maintaining the quality of the video signal. In this paper, the algorithm proposed is called Orthogonal-Diamond Search (ODS) which employs an orthogonal-shaped search pattern in the first step and then is switched into diamond-shaped search pattern for the next step. The proposed algorithm and several established algorithms namely Three Step Search (TSS), New-Three-Step Search (NTSS), Four-Step Search (4SS), Diamond Search (DS) and Hexagon-Diamond Search (HDS) are implemented using MATLAB and their performance are being compared and analyzed in terms of number of search point, peak signal-to-noise ratio (PSNR) and computational complexity. Simulation result show that the proposed algorithm can find motion vector with fever number of search points while maintains close performance of video quality with other selected algorithms.

Block-matching algorithm is the most common technique applied in block-based motion estimation technique. There are several block-matching algorithm based on block-based motion estimation techniques have been developed. Full search (FS), three step search (TSS), new three step search (NTSS), diamond search (DS) and hexagon based search (HS) are the most well known block-matching algorithm. These techniques are applied to video sequences to remove the temporal redundancy for compression purposes and to gauge the motion vector estimation. In addition, the mentioned block-matching algorithms are the baseline techniques that have been used to further develop all the enhanced or improved algorithms. In order to develop the proposed methods, the baseline techniques are studied to develop the proposed algorithms. This chapter proposes modelling of fast unrestricted hexagon search (FUHS16) and unrestricted hexagon-diamond search (UHDS16) algorithms for motion vector estimation, which is based on the theory and application of block-based motion estimation. Both of these algorithms are designed using 16 × 16 block size. In particular, the motion vector estimation, quality performance, computational complexity, and elapsed processing time are emphasised. These parameters have been used to measure the experimental results. It is the aim of this study that this work provides a common framework with which to evaluate and understand block-based matching motion estimation performance. On the theoretical side, four fundamental issues are explored: (1) division of frame, (2) basic block-based matching, (3) motion vector estimation, and (4) block-matching algorithm development. Various existing block-matching motion estimation algorithms have been analysed to develop the fundamental research. Based on the theoretical and fundamental research analysis the FUHS16 and UHDS16 algorithms using 16 × 16 block-based motion estimation formulations were developed. To improve the UHDS16 algorithm, 8 × 8 block-matching technique has been tested. The 8 × 8 block-matching technique is known as UHDS8. The results show positive improvements. From an application perspective, the UHDS8 algorithm efficiently captured the motion vectors in many video sequences. For example, in video compression, the use of motion vectors on individual macro-blocks optimized the motion vector information. The UHDS8 algorithm also offers improvement in terms of image quality performance, computational complexity and elapsed processing time. Thus, this chapter offers contributions in certain areas such as reducing the mechanism of computational complexity in estimating the motion from the video sequences. In particular, the FUHS16, UHDS16 and UHDS8 algorithms were developed to estimate the motion vectors field in the video sequences. Theoretical analysis block-based matching criteria are adapted to FUHS16, UHDS16 and UHDS8 algorithms, which are based on search points technique. Basically, the proposed of FUHS16, UHDS16 and UHDS8 algorithm produces the best motion vector estimation finding based on the block-based matching criteria. Besides that, the UHDS8 algorithm also improves the image quality performances and the search points in terms of the computational complexity. Overall, the study shows that the UHDS8 algorithm produces better results compared to the FUHS16 and UHDS16 algorithm.

In block motion estimation, a search pattern with a different shape or size has a very important impact on search speed and distortion performance. A square-shaped search pattern is adopted in many popular fast algorithms. Recently, a diamond-shaped search pattern was introduced in fast block motion estimation and has exhibited a faster search speed. Based on an in-depth examination of the influence of the search pattern on speed performance, we propose a novel algorithm using a hexagon-based search pattern to achieve further improvement. The hexagon-based search pattern is investigated in comparison with diamond search pattern and demonstrates significant speedup gain over the diamond-based search. Analysis shows that a speed improvement rate of the hexagon-based search (HEXBS) algorithm over the diamond search (DS) algorithm can be over 80% for locating some motion vectors in certain scenarios. In short, the proposed HEXBS algorithm can find the same motion vector with fewer search points than the DS algorithm. Generally speaking, the larger the motion vector, the more search points the. HEXBS algorithm can save, which is further justified by experimental results.

The full search block-matching algorithm is the simplest, but computationally very intensive approach. In recent years there was substantial progress in block motion estimation algorithms. Important milestones on this path were such algorithms as two-dimensional logarithmic search, three-step search, four step search, and diamond search. All these methods try to minimize the amount of search points applying sum of absolute differences (SAD) or equivalent metrics for each point. There were some works that studied partial SAD (PSAD) but mostly concentrated on a constant decimation factor. What we tried to study in this work is the performance of one of the best block matching search algorithms in combination with adaptive PSAD as a matching metric. The idea is that we use original motion estimation based on spatio-temporal correlation method, but instead of using SAD as a matching metric we use PSAD with adaptively chosen decimation factor. Our simulation results show that for high motion sequences PSNR degradation between full search and the proposed method was around 0.1-0.7 dB. The computational complexity reduction of 650-1700 times (compared with the full search) and 9 times (compared to the original method) is pretty big and may be well worth this video quality decrease. In the case of more static sequences PSNR degradation between full search and the original motion estimation method was around 0 dB. When we compare the original method with the proposed one the degradation increases to 0.1 dB. The computational complexity reduction was around 1600-1700 times (compared with the full search) and 5-7 times (compared to the original method).

In this paper, a modified diamond search (MDS) algorithm is proposed for fast motion estimation based on the well known diamond search (DS) algorithm. A set of computationally efficient algorithms that can be applied to any block matching algorithm and is applied to the DS as a study case achieves higher complexity reduction than DS algorithm without further relative PSNR (peak signal to noise ratio) degradation compared to full search (FS). First, dynamic internal stop search (DISS) algorithm is used to reduce the internal redundant SAD (sum of absolute difference) operations between the current and the candidate blocks using an accurate dynamic threshold. Second, a dynamic external stop search (DESS) greatly reduces the unnecessary operations by skipping all the irrelevant blocks in the search area. In addition, early search termination and adaptive pattern selections techniques are applied to the proposed MDS as initialization steps to achieve even higher complexity reduction. The accuracy of the proposed model threshold equations guarantee not to fall into a local minima. Experiments show that the proposed MDS algorithm reduces the computations greatly up to 99% and 20% compared with the conventional FS algorithm and DS respectively with no significant degradation in both the PSNR and the bit-rate.

This work presents an efficient method to map Motion Estimation (ME) algorithms onto General Purpose Graphic Processing Unit (GPGPU) architectures using CUDA programming model. Our method jointly exploits the massive parallelism available in current GPGPU devices and the parallelization potential of ME algorithms: Full Search (FS) and Diamond Search (DS). Our main goal is to evaluate the feasibility of achieving real-time high-definition video encoding performance running on GPUs. For comparison reasons, multi-core parallel and distributed versions of these algorithms were developed using OpenMP and MPI (Message Passing Interface) libraries, respectively. The CUDA-based solutions achieve the highest speed-up in comparison with OpenMP and MPI versions for both algorithms and, when compared to the state-of-the-art, our FS and DS solutions reach up to 18x and 11x speed-up, respectively.

Motion estimation (ME) is a process of correlating the frames by pointing the blocks in the candidate frame similar to those in the previous frame. Hexagonal Search (HS) reduces 10–15% search points over Diamond Search (DS) with negligible Peak Signal to Noise Ratio (PSNR) loss. Adapting an optimization will achieve a massive improvement on the search process. The proposed HS-GA method combines the HS with genetic algorithm (GA) to optimize ME. The HS-GA method reduces 72% on average search points pre block (ASPB) with PSNR loss of 2.5 dB and single generation. If the GA is executed with 10 generations the PSNR loss is reduced to 0.48 dB, but ASPB drastically increase to ∼316%. The proposed work aims at multi objective on selection of better chromosomes and on control of generations to avoid the unnecessary generations to improve the GA. This process is named HSIGA(HS with Intelligent GA). The proposed HSIGA adapts five intelligent techniques like Histogram to decide new generations, Region based chromosome selection, Mutation on inner search gene, second rank valley point stopping criteria and interlaced HS to improve search process with negligible PSNR loss with in affordable search.

Block motion estimation using full search is computationally intensive. Previously proposed fast algorithms reduce the computation by limiting the number of searching locations. This is accomplished at the expense of less accuracy of motion estimation and gives rise to an appreciably higher mean squared error (MSE) for motion compensated images. We present a new fast and efficient search algorithm for block motion estimation that produces better quality performance and less computational time compared with a three-step search (TSS) algorithm. The proposed algorithms are based on the ideas of the dithering pattern for pixel decimation, multiple-candidate for pixel-decimation-based full search, and center-based distribution of the motion vector. From the experimental results, the proposed algorithm is superior to the TSS in both quality performance (about 0.2 dB) and computational complexity (about half).

움직임 추정은 동영상 압축에서 영상 화질과 인코더 속도에 대하여 중요한 역할을 하지만, 많은 수행 시간을 요구한다. H.264/AVC에서 움직임 추정에 소요되는 수행 시간을 줄이면서 화질을 유지하기 위하여 본 논문에서는 정화소와 부화소 움직임 추정 기법을 제안하였다. 본 논문에서는 정화소 움직임 추정을 위하여 계층적인 탐색 기법을 사용하였고, 정확한 움직임 추정을 위하여 블록 크기에 따라 부화소 움직임 추정 패턴을 적응적으로 결정하였다. 제안한 정화소 움직임 추정 탐색 기법은 대칭적 십자가-엑스 탐색 패턴, 다중 사각형 탐색 패턴, 다이아몬드 탐색 패턴들로 이루어져 있다. 이 탐색 패턴들은 블록 움직임이 수직으로 크거나 블록 움직임이 크면서 규칙적인 영상에서 국부적 최소화 문제를 해결하고 움직임 추정에 소요되는 시간을 줄이기 위하여 탐색 영역 내에 탐색 점들을 규칙적, 대칭적으로 배치하였다. 제안한 부화소 움직임 추정 탐색 기법은 부화소 움직임 추정을 위하여 기존의 전역 부화소 탐색 패턴, 중앙 편향적 부화소 탐색 패턴과 제안한 부화소 움직임 탐색패턴들을 사용한다. 그리고 블록의 크기에 따라 3가지의 부화소 탐색 패턴들 중 한 패턴이 부화소 움직임 추정을 위해 적응적으로 결정된다. 블록의 크기에 따라 적응적으로 부화소 탐색 패턴이 결정되므로 보다 정확하게 부화소 움직임 추정을 수행할 수 있다. 제안한 기법을 전역 탐색 기법과 비교하였을 때 약 5.2배의 속도 향상을 가져왔으며, 영상 화질에 있어서 약 0.01 (dB)정도 성능 저하를 보였다. 반면에, 비대칭 다중육각형 탐색 기법과 비교하였을 때 움직임 추정 속도와 화질에 있어서 각각 약 1.2배와 약 0.02 (dB)정도 향상을 보였다. Motion estimation (ME) plays an important role in digital video compression. But it limits the performance of image quality and encoding speed and is computational demanding part of the encoder. To reduce computational time and maintain the image quality, integer pel and fractional pel ME methods are proposed in this paper. The proposed method for integer pel ME uses a hierarchical search strategy. This strategy method consists of symmetrical cross-X pattern, multi square grid pattern, diamond patterns. These search patterns places search points symmetrically and evenly that can cover the overall search area not to fall into the local minimum and to reduce the computational time. The proposed method for fractional pel uses full search pattern, center biased fractional pel search pattern and the proposed search pattern. According to block sizes, the proposed method for fractional pel decides the search pattern adaptively. Experiment results show that the speedup improvement of the proposed method over Unsymmetrical cross Multi Hexagon grid Search (UMHexagonS) and Full Search (FS) can be up to around <TEX>$1.2{\sim}5.2$</TEX> times faster. Compared to image quality of FS, the proposed method shows an average PSNR drop of 0.01 dB while showing an average PSNR gain of 0.02 dB in comparison to that of UMHexagonS.

The upcoming video coding standard, MPEG-4 AVC/JVT/H.264, motion estimation is allowed to use multiple references and multiple block sizes to improve the rate-distortion performance. However, full exhaustive search of all block sizes is computational intensive with complexity increasing linearly to the number of allowed reference frame and block size. A novel search algorithm, predict hexagon search (PHS), is proposed. The PHS pattern is applied by the comparison with the hexagon based search pattern. It can predict the hexagon search pattern in horizontal or vertical direction. Analysis shows that the speed improvement of the PHS over the diamond search (DS) and the hexagon based search (HEXBS) is about 58% and 53% respectively.

Most of the fast motion estimation algorithms based on search-point pattern are only good at handling videos with small motions, for example, block-based gradient descent search, diamond search and hexagonal-based search. An adaptive motion estimation algorithm which can switch between search patterns for different video contents should work better than a single search pattern algorithm. In this paper, a simple classifier based on error descent rate (EDR) is proposed. This classifier uses a very few number of search points to predict whether the global minimum is far away or near the center of the search window. If it is far away, a search pattern which is good at searching large motions is used. Otherwise, a pattern good at searching small motions is applied. The proposed search patterns switching (SPS) algorithm performs well for all kinds of video contents.

Many suboptimal motion vector search algorithms have been proposed because the full search algorithm, which is an optimal method, requires huge computational requirements. These algorithms find motion vectors simply from the center of the search window. In this paper we propose an efficient motion vector search algorithm (GLS), which exploits the global motion information obtained from the previous three frames and the local motion information regarding the motion vectors of the neighboring blocks of the current block in order to predict the initial search point. GLS searches for a motion vector from this initial search point, instead of the center of the search window, using either the diamond search algorithm (DS) or the unrestricted small diamond search algorithm (USDS) which performs its search always with a smaller diamond search pattern. USDS has the same search pattern as that of the last search step in DS. Experimental results show that GLS is a faster and more accurate motion vector search method than other suboptimal methods.

To enable wireless Internet and other data services using mobile appliances, there is a critical need to support content rich cellular data communication, including voice, text, image and video. However, mobile communication of multimedia content has several bottlenecks, including limited bandwidth of cellular networks, channel noise, and battery constraints of the appliances. This paper is a review of the block matching algorithms used for motion estimation in video compression. It implements and compares 7 different types of block matching algorithms such as, Exhaustive Search, Three Step Search (TSS), New Three Step Search (NTSS), Simple and Efficient Search (SES), Four Step Search (4SS), Diamond Search (DS), Adaptive Rood Pattern Search (ARPS) and conclude the better block estimation algorithm for video compression. The algorithms that are evaluated in this paper are widely accepted by the video compressing community and have been used in implementing various standards. Of the various algorithms studied and simulated ARPS turns out to be the better block matching algorithm for motion estimation.

In single viewpoint video coding, there are many fast block matching motion estimation algorithms proposed, such as three-step search, four-step search, diamond search as well as hexagon-based search and so on. However, experimental analysis show that these algorithms are not suitable for using directly in Multiview View Coding (MVC). Since the increased search range, the larger format of multiview video as well as the correlations between inter-view frames are not considered by these algorithms, they may easy led the block matching search into local minimum, the Rate-Distortion (R-D) performance will degrade dramatically. In this paper, we propose a novel multiple hexagon search algorithm to address this problem. Firstly, according to the original initial search point, four sub-search windows are constructed. Then, the hexagon based search algorithm will be performed respectively in the four sub-search windows. The final result is the best search point with the minimum R-D cost among the best points in the four sub-search windows. In order to trade off the computational complexity and R-D performance, two adaptive early termination strategies are proposed. The experimental results show that the proposed algorithm yields a quite promising coding performance in terms of R-D performance and computational complexity. Especially, the proposed algorithm can work well in multiview video sequences with various motion and disparity activities.

Efficient inner search for faster diamond search