The Experts below are selected from a list of 1470 Experts worldwide ranked by ideXlab platform

Ruobing Zou - One of the best experts on this subject based on the ideXlab platform.

  • ISCAS - Fast sub-Pixel motion estimation with simplified modeling in HEVC
    2012 IEEE International Symposium on Circuits and Systems, 2012
    Co-Authors: Wei Dai, Lin Sun, Ruobing Zou
    Abstract:

    Motion estimation (ME) is one of the key elements in video coding standard which eliminates the temporal redundancies between successive frames. In recent international video coding standards, sub-Pixel ME is proposed for its excellent coding performance. Compared with Integer-Pixel ME, sub-Pixel ME needs interpolation to get the value in sub-Pixel position. Also, Hadamard transform will be applied in order to achieve better performance. Therefore, it is becoming more and more critical to develop fast sub-Pixel ME algorithms. In this paper, a novel fast sub-Pixel ME algorithm is proposed which makes full use of 8 neighboring Integer-Pixel points. This algorithm models the error surface in sub-Pixel position by a second order function with five parameters two times to predict the best sub-Pixel position. Experimental results show that the proposed method can reduce the complexity significantly with negligible quality degradation.

  • ICASSP - A novel fast two step sub-Pixel motion estimation algorithm in HEVC
    2012 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2012
    Co-Authors: Wei Dai, Lin Sun, Chao Pang, Ruobing Zou
    Abstract:

    Motion estimation (ME) is one of the most time consuming parts in video coding standard. As fast Integer-Pixel ME algorithm becoming more and more powerful, it is important to develop fast sub-Pixel ME algorithm since the computational complexity of sub-Pixel ME compared to Integer-Pixel ME has become relatively significant. In this paper, a novel fast sub-Pixel ME algorithm is proposed. This algorithm first approximates the error surface of the sub-Pixel position by a second order function and predicts the minimum point by minimizing the function at half-Pixel accuracy. Then another second order approximation within a smaller area which is determined by the previous step is modeled to predict the best sub-Pixel position. Experimental results show that the proposed method can reduce the sub-Pixel search points significantly with negligible quality degradation.

Wang Kuang - One of the best experts on this subject based on the ideXlab platform.

  • Fractional Pixel Motion Estimation based on Prediction of Flat Regions for H.264
    Journal of Image and Graphics, 2008
    Co-Authors: Wang Kuang
    Abstract:

    Motion estimation(ME) consumes most of the computational resource in a video encoder system.H.264 adopts multi-mode ME and quarter-pel accuracy fractional Pixel search,which brings about large scale of computational cost not only to Integer Pixel ME but also to fractional Pixel ME.However,the computational cost of Integer Pixel ME has been greatly reduced with the development of fast Integer search algorithms.Therefore,fast fractional Pixel ME algorithms become significantly important for real-time applications.A novel fractional Pixel motion estimation based on prediction of flat regions of an image is first proposed in this paper.It reduces fractional pel search points efficiently by predicting flat homogeneous regions of the image.Experimental results show that compared to the full fractional Pixel search,the proposed method can reduce 22% to 63% of fractional Pixel search points while keeping the image quality and compression rate almost unchanged.

  • Half-Pixel Motion Estimation Based on Linear Prediction
    Journal of Image and Graphics, 2007
    Co-Authors: Wang Kuang
    Abstract:

    In video coding system,motion estimation at half-Pixel accuracy can obviously enhanced coding efficiency compared to the motion estimation at Integer-Pixel accuracy only.However it requires more computation at the same time.In order to reduce the computation and while enhance the speed of motion estimation at half-Pixel,we proposed a novel half-Pixel motion estimation algorithm named half-Pixel motion estimation based on linear prediction(BLPHME) for video coding in this paper.The key point of the algorithm is setting up a linear model by analyzing the relativity between the results of Integer-Pixel search and half-Pixel search.Then we can modify the threshold dynamically for each frame.By doing so,it can skip over the blocks that can't be benefited from the half-Pixel search based on the block size.Experimental results show that significant reduction in computation of motion estimation is achieved together with the increment in bit rate by using the proposed method,but without obvious increment in bit rate and visible loss in video fidelity and increment in bit rate.Moreover,the proposed algorithm can be combined with any of the fast motion estimation algorithm at Integer-Pixel or half-Pixel accuracy to further reduce the complexity.

  • Fast Two Step Search Algorithm for Half-Pixel
    Computer Engineering, 2006
    Co-Authors: Wang Kuang
    Abstract:

    A fast two-step search algorithm for half-Pixel motion estimation is proposed based on the fact that the SAD distortion function increases monotonously as the search location moves away from the sub-Pixel minimum within ± 1 Pixel neighborhood of the result of Integer-Pixel search.Experimental results show that significant reduction in computation is achieved by using the propose method,without visible loss in video fidelity.

Wei Dai - One of the best experts on this subject based on the ideXlab platform.

  • ICIP - A robust interpolation-free approach for sub-Pixel accuracy motion estimation
    2013 IEEE International Conference on Image Processing, 2013
    Co-Authors: Wei Dai, Wenjing Zhu, Pengfei Wan
    Abstract:

    Motion estimation (ME) is one of the key elements in video coding standard which eliminates the temporal redundancy by using a motion vector (MV) to indicate the best match between the current frame and reference frame. A coarse to fine process is taken to find the best MV. First of all, Integer-Pixel ME finds a coarse MV and followed by the sub-Pixel ME around the best Integer-Pixel point. The sub-Pixel ME plays an important role in improving the coding efficiency. However, the computational complexity of searching one sub-Pixel point is much higher than the Integer-Pixel point searching because of the interpolation and Hadamard transform operation. In this paper, an accurate optimal sub-Pixel position prediction algorithm is presented. With the information of the 8 neighboring Integer-Pixel points, the optimal sub-Pixel position is predicted directly without explicitly solving model parameters. Moreover, an outlier rejection scheme is applied to improve the robustness of the proposed algorithm. Experimental results show that the proposed algorithm outperforms the state of the art interpolation-freesub-Pixel ME algorithms.

  • ISCAS - Fast sub-Pixel motion estimation with simplified modeling in HEVC
    2012 IEEE International Symposium on Circuits and Systems, 2012
    Co-Authors: Wei Dai, Lin Sun, Ruobing Zou
    Abstract:

    Motion estimation (ME) is one of the key elements in video coding standard which eliminates the temporal redundancies between successive frames. In recent international video coding standards, sub-Pixel ME is proposed for its excellent coding performance. Compared with Integer-Pixel ME, sub-Pixel ME needs interpolation to get the value in sub-Pixel position. Also, Hadamard transform will be applied in order to achieve better performance. Therefore, it is becoming more and more critical to develop fast sub-Pixel ME algorithms. In this paper, a novel fast sub-Pixel ME algorithm is proposed which makes full use of 8 neighboring Integer-Pixel points. This algorithm models the error surface in sub-Pixel position by a second order function with five parameters two times to predict the best sub-Pixel position. Experimental results show that the proposed method can reduce the complexity significantly with negligible quality degradation.

  • ICASSP - A novel fast two step sub-Pixel motion estimation algorithm in HEVC
    2012 IEEE International Conference on Acoustics Speech and Signal Processing (ICASSP), 2012
    Co-Authors: Wei Dai, Lin Sun, Chao Pang, Ruobing Zou
    Abstract:

    Motion estimation (ME) is one of the most time consuming parts in video coding standard. As fast Integer-Pixel ME algorithm becoming more and more powerful, it is important to develop fast sub-Pixel ME algorithm since the computational complexity of sub-Pixel ME compared to Integer-Pixel ME has become relatively significant. In this paper, a novel fast sub-Pixel ME algorithm is proposed. This algorithm first approximates the error surface of the sub-Pixel position by a second order function and predicts the minimum point by minimizing the function at half-Pixel accuracy. Then another second order approximation within a smaller area which is determined by the previous step is modeled to predict the best sub-Pixel position. Experimental results show that the proposed method can reduce the sub-Pixel search points significantly with negligible quality degradation.

Guee-sang Lee - One of the best experts on this subject based on the ideXlab platform.

  • Hierarchical Integer Pixel and Adaptive Fractional Pixel Motion Estimation
    2008 IEEE 8th International Conference on Computer and Information Technology Workshops, 2008
    Co-Authors: Hyo-sun Yoon, Hye-suk Kim, Mi-young Kim, Lai Nga, Guee-sang Lee
    Abstract:

    Motion estimation (ME) plays an important role in digital video compression, since it can significantly affect the image quality, the encoding speed and the compression ratio. ME is very computationally demanding part of the encoder. To reduce computational complexity and to maintain the good image quality, Integer Pixel and fractional Pixel ME methods are proposed in this paper. For Integer Pixel ME, a hierarchical search strategy is proposed. This strategy method consists of symmetrical cross search pattern, multi square grid pattern, large and small diamond search patterns. To reduce the computational time and not to fall into the local minimum, these search patterns place search points symmetrically and evenly in the overall search area. After Integer Pixel ME, the adaptive fractional Pixel ME method is performed. This fractional Pixel ME method decides the search pattern adaptively according to the block size. Experimental results show that the speedup improvement of the proposed method over unsymmetrical cross multi hexagon grid search (UMHexagonS) and full search (FS) can be about 1.2~ 5.2 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.

  • KES - Fast Half Pixel Motion Estimation Based on the Spatial Correlation
    Lecture Notes in Computer Science, 2004
    Co-Authors: Hyo-sun Yoon, Guee-sang Lee
    Abstract:

    Motion estimation is an important part of video encoding systems, because it can significantly affect the output quality of an encoded sequence. Most of the advanced techniques for motion estimation consist of two stages, the Integer Pixel motion estimation and the half Pixel motion estimation. Although many fast Integer Pixel motion estimation algorithms have been developed, the performance of current methods for half Pixel motion estimation still has room for improvement. In this paper, we propose a new algorithm for half Pixel motion estimation which exploits the spatial correlation between Integer and half pixle motion vectors. The proposed algorithm adaptively decides the search range of half Pixel points considering the correlation of the motion vectors around the point of interest. The experiment results show that the proposed method outperforms most of existing methods in computaion time by reducing the number of search points with little or no degradation in image quality. Even when compared to the full half Pixel search method, it shows the search point reducton upto 95% with only 0.01 ~ 0.09 (dB) degradation of image quality in terms of PSNR.

  • CIS - Fast and accurate half Pixel motion estimation using the property of motion vector
    Computational and Information Science, 2004
    Co-Authors: Migyoung Jung, Guee-sang Lee
    Abstract:

    To estimate an accuracy motion vector (MV), a two step search is generally used. In the first step, Integer Pixel points within a search area are examined to find the Integer Pixel MV. Then, in the second step, 8 half Pixel points around the selected Integer Pixel MV are examined and the best matching point is chosen as the final MV. Many fast Integer Pixel motion estimation (ME) algorithms can be found by examining less than about 10 search points. However, the half Pixel ME requires huge computational complexity. In this paper, We propose a new fast algorithm for half Pixel ME that reduces the computational overhead by limiting the number of interpolations of the candidate half Pixel points. The proposed method based on the property of MVs and the correlations between Integer Pixel MVs and half Pixel MVs. Experimental results show that the speedup improvement of the proposed algorithm over a full half Pixel search (FHPS), horizontal and vertical directions as references (HVDR), chen's half Pixel search algorithm (CHPS-1) and a parabolic prediction-based fast half-Pixel search (PPHPS) can be up to 1.4 ~ 3.9 times on average. Also the image quality improvement can be better up to 0.05(dB) ~ 0.1(dB) compare with CHPS and PPHPS.

  • CIS - An efficient half Pixel motion estimation algorithm based on spatial correlations
    Computational and Information Science, 2004
    Co-Authors: Hyo-sun Yoon, Guee-sang Lee, Yoon-jeong Shin
    Abstract:

    Motion estimation is an important part of video encoding systems, because it can significantly affect the output quality and the compression ratio. Motion estimation which consists of Integer Pixel motion estimation and half Pixel motion estimation is very computationally intensive part. To reduce the computational complexity, many methods have been proposed in both Integer Pixel motion estimation and half Pixel motion estimation. For Integer Pixel motion estimation, some fast methods could reduce their computational complexity significantly. There remains, however, room for improvement in the performance of current methods for half Pixel motion estimation. In this paper, an efficient half Pixel motion estimation algorithm based on spatial correlations is proposed to reduce the computational complexity. According to spatially correlated information, the proposed method decides whether half Pixel motion estimation is performed or not for the current block. Experimental results show that the proposed method outperforms most of current methods in computation complexity by reducing the number of search points with little degradation in image quality. When compared to full half Pixel search method, the proposed algorithm achieves the search point reduction up to 96% with only 0.01 ~ 0.1 (dB) degradation of image quality.

Hong Miao - One of the best experts on this subject based on the ideXlab platform.

  • Sub-Pixel displacement algorithm in temporal sequence digital image correlation based on correlation coefficient weighted fitting
    Optics and Lasers in Engineering, 2018
    Co-Authors: Hong Miao
    Abstract:

    Abstract Digital image correlation (DIC) is a non-contact technique that is used widely for deformation measurement, but it has problems due to the large amount of calculations required, which make it time consuming. Sub-Pixel displacement methods are usually based on spatial correlations, which only consider the spatial continuity of the deformation and ignore temporal continuity. This study proposes a DIC algorithm to calculate sub-Pixel displacement combining spatial and temporal correlations. A fast Integer-Pixel displacement algorithm is employed to calculate full field Integer-Pixel displacement at different deformation times. Then the moving least squares fitting technique with a weighted function based on the correlation coefficient is used to fit each point's Integer-Pixel displacement along the time axis, allowing the full field sub-Pixel displacement to be calculated for every moment. Experimental results demonstrated the accuracy and efficiency of the proposed algorithm. This achieved the same accuracy as tradition spatial correlation algorithms. Computation efficiency was improved almost 8 fold compared with the IC-GN algorithm, largely due to the Integer-Pixel displacement calculation; sub-Pixel displacement computation only accounted for approximately 2.7% with 41 Pixel subsets. Computational efficiency could be further enhanced if a faster Integer-Pixel displacement calculation method was developed or parallel processing was incorporated.