Motion compensation for image compression: pel-recursive motion estimation algorithm

In motion pictures there is a certain amount of redundancy between consecutive frames. These redundancies can be exploited by using interframe prediction techniques. To further enhance the efficiency of interframe prediction, motion estimation and compensation, various motion compensation techniques can be used. There are two distinct techniques for motion estimation block matching and pel-recursive block matching has been widely used as it produces a better signal-to-noise ratio or a lower bit rate for transmission than the pel-recursive method. In this thesis, various pel-recursive motion estimation techniques such as steepest descent gradient algorithm have been considered and simulated. [Continues.

Optimization of the motion estimation for parallel embedded systems in the context of new video standards

15 pagesInternational audienceThe effciency of video compression methods mainly depends on the motion compensation stage, and the design of effcient motion estimation techniques is still an important issue. An highly accurate motion estimation can significantly reduce the bit-rate, but involves a high computational complexity. This is particularly true for new generations of video compression standards, MPEG AVC and HEVC, which involves techniques such as different reference frames, sub-pixel estimation, variable block sizes. In this context, the design of fast motion estimation solutions is necessary, and can concerned two linked aspects: a high quality algorithm and its effcient implementation. This paper summarizes our main contributions in this domain. In particular, we first present the HME (Hierarchical Motion Estimation) technique. It is based on a multi-level refinement process where the motion estimation vectors are first estimated on a sub-sampled image. The multi-levels decomposition provides robust predictions and is particularly suited for variable block sizes motion estimations. The HME method has been integrated in a AVC encoder, and we propose a parallel implementation of this technique, with the motion estimation at pixel level performed by a DSP processor, and the sub-pixel refinement realized in an FPGA. The second technique that we present is called HDS for Hierarchical Diamond Search. It combines the multi-level refinement of HME, with a fast search at pixel-accuracy inspired by the EPZS method. This paper also presents its parallel implementation onto a multi-DSP platform and the its use in the HEVC context

HDS, a real-time multi-DSP motion estimator for MPEG-4 H.264 AVC high definition video encoding

International audienceH.264 AVC video compression standard achieves high compression rates at the cost of a high encoder complexity. The encoder performances are greatly linked to the motion estimation operation which requires high computation power and memory bandwidth. High definition context magnifies the difficulty of a real-time implementation. EPZS and HME are two well-known motion estimation algorithms. Both EPZS and HME are implemented in a DSP and their performances are compared in terms of both quality and complexity. Based on these results, a new algorithm called HDS for Hierarchical Diamond Search is proposed. HDS motion estimation is integrated in a AVC encoder to extract timings and resulting video qualities reached. A real-time DSP implementation of H.264 quarter-pixel accuracy motion estimation is proposed for SD and HD video format. Furthermore HDS characteristics make this algorithm well suited for H.264 SVC real-time encoding applications

Image sequence restoration by median filtering

Median filters are non-linear filters that fit in the generic category of order-statistic filters. Median filters are widely used for reducing random defects, commonly characterized by impulse or salt and pepper noise in a single image. Motion estimation is the process of estimating the displacement vector between like pixels in the current frame and the reference frame. When dealing with a motion sequence, the motion vectors are the key for operating on corresponding pixels in several frames. This work explores the use of various motion estimation algorithms in combination with various median filter algorithms to provide noise suppression. The results are compared using two sets of metrics: performance-based and objective image quality-based. These results are used to determine the best motion estimation / median filter combination for image sequence restoration. The primary goals of this work are to implement a motion estimation and median filter algorithm in hardware and develop and benchmark a flexible software alternative restoration process. There are two unique median filter algorithms to this work. The first filter is a modification to a single frame adaptive median filter. The modification applied motion compensation and temporal concepts. The other is an adaptive extension to the multi-level (ML3D) filter, called adaptive multi-level (AML3D) filter. The extension provides adaptable filter window sizes to the multiple filter sets that comprise the ML3D filter. The adaptive median filter is capable of filtering an image in 26.88 seconds per frame and results in a PSNR improvement of 5.452dB. The AML3D is capable of filtering an image in 14.73 seconds per frame and results in a PSNR improvement of 6.273dB. The AML3D is a suitable alternative to the other median filters

Motion‐Compensated Transform Coding

Interframe Hybrid Transform/dpcm Coders Encode Television Signals by Taking a Spatial Transform of a Block of Picture Elements in a Frame and Predictively Coding the Resulting Coefficients using the Corresponding Coefficients of the Spatial Block at the Same Location in the Previous Frame. These Coders Can Be Made More Efficient for Scenes Containing Objects in Translational Motion by First Estimating the Translational Displacement of Objects and Then using Coefficients of a Spatially Displaced Block in the Previous Frame for Prediction. This Paper Presents Simulation Results for Such Motion‐compensated Transform Coders using Two Algorithms for Estimating Displacements. the First Algorithm, Which is Developed in a Companion Paper, Recursively Estimates the Displacements from the Previously Transmitted Transform Coefficients, Thereby Eliminating the Need to Transmit the Displacement Estimates. the Second Algorithm, Due to Limb and Murphy, Estimates Displacements by Taking Ratios of Accumulated Frame Difference and Spatial Difference Signals in a Block. in This Scheme, the Displacement Estimates Are Transmitted to the Receiver. Computer Simulations on Two Typical Real‐life Sequences of Frames Show that Motion‐compensated Coefficient Prediction Results in Coder Bit Rates that Are 20 to 40 Percent Lower Than Conventional Interframe Transform Coders using Frame Difference of Coefficients. Comparisons of Bit Rates for Approximately the Same Picture Quality Show that the Two Methods of Displacement Estimation Are Quite Similar in Performance with a Slight Preference for the Scheme with Recursive Displacement Estimation. © 1979 the Bell System Technical Journa

Hierarchical motion estimation for side information creation in Wyner-Ziv video coding

Recently, several video coding solutions based on the distributed source coding paradigm have appeared in the literature. Among them, Wyner-Ziv video coding schemes enable to achieve a flexible distribution of the computational complexity between the encoder and decoder, promising to fulfill requirements of emerging applications such as visual sensor networks and wireless surveillance. To achieve a performance comparable to the predictive video coding solutions, it is necessary to increase the quality of the side information, this means the estimation of the original frame created at the decoder. In this paper, a hierarchical motion estimation (HME) technique using different scales and increasingly smaller block sizes is proposed to generate a more reliable estimation of the motion field. The HME technique is integrated in a well known motion compensated frame interpolation framework responsible for the creation of the side information in a Wyner-Ziv video decoder. The proposed technique enables to achieve improvements in the rate-distortion (RD) performance up to 7 dB when compared to H.263+ Intra and 3 dB when compared to H.264/AVC Intra

Low complexity hardware oriented H.264/AVC motion estimation algorithm and related low power and low cost architecture design

制度:新 ; 報告番号:甲2999号 ; 学位の種類:博士(工学) ; 授与年月日:2010/3/15 ; 早大学位記番号:新525