检索结果-内蒙古大学图书馆

Fast mode decision scheme using sum of the absolute difference-based Bayesian model for the H.264/AVC video standard

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IET SIGNAL PROCESSING 2014年第5期8卷 530-539页

作者： Kim, Jongho Lee, Jong-Hyeok Kim, Byung-Gyu Choi, Jin Soo Elect & Telecommun Res Inst Visual Media Res Sect Realist Broadcasting Media Res Dept Taejon 305606 South Korea SunMoon Univ Dept Comp Engn A San South Korea

H.264/AVC is the most widely used recent video coding standard. It provides a high encoding efficiency but it also has a high computational complexity. The block mode decision for motion estimation is the most time-consuming procedure. A complexity reduction method for the block mode decision procedure is proposed. To reduce the complexity, all block modes are divided into several candidate block mode groups. The sum of the absolute difference ( SAD) value, including the motion cost of each mode, is used as a classification feature to divide the block modes into several groups. A refinement method using a Bayesian model based on the average SAD value is also proposed. For B-slices, a differential block mode allocation method is suggested. A different number of candidate modes are allocated for lists ( list 0, list 1) based on the SAD value of each list after 16 x 16 block motion estimation. The proposed method achieves an average time-saving for the total encoding time of 65% for IPPP and 66.01% for the hierarchical-B structure.

关键词： Computer vision and image processing techniques image and video coding hierarchical-B-slices structure IPPP Game theory Bayesian model motion estimation block codes video coding decision theory fast mode decision scheme block motion estimation complexity reduction method Bayes methods differential block mode allocation method video signal processing SAD value sum of the absolute difference value block mode decision procedure Computational complexity computational complexity refinement method image classification H.264-AVC video coding standard

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Dynamic frame-skipping transcoding with motion information considered

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IET image PROCESSING 2007年第4期1卷 335-342页

作者： Shu, H. Chau, L. -P. Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore

Frame-skipping transcoding is an efficient tool for reducing the bit rate when transmitting precoded video over bandwidth-constrained channels. In this process, the motion information is an important factor to be considered. Traditional methods consider only the motion activity information in dynamic frame-skipping transcoding. The concept of motion change is introduced to evaluate motion continuity. Combined with the motion activity information, these two parts of motion information are used to dynamically skip frames without seriously affecting the visual quality. A new frame-skipping scheme with a variable length prediction window is also proposed. Experimental results show that the proposed method can present a smooth frame rate variation, and well preserve the original motion information with tolerable delay. At the same time, spatial quality is also improved.

关键词： spatial quality video precoding precoding dynamic frame-skipping transcoding bandwidth-constrained channels variable length prediction window video coding transcoding image and video coding motion continuity motion activity information video signal processing motion change smooth frame rate variation image motion analysis

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Fusion framework for multi-focus images based on compressed sensing

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IET image PROCESSING 2013年第4期7卷 290-299页

作者： Kang, Bin Zhu, Wei-Ping Yan, Jun Nanjing Univ Posts & Telecommun Coll Commun & Informat Engn Nanjing 210003 Jiangsu Peoples R China Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada

In this study, an efficient image fusion framework for multi-focus images is proposed based on compressed sensing. The new fusion framework consists of three parts: image sampling, measurement fusion and image reconstruction. First, the dual-channel pulse coupled neural network model is used in the image sampling part as an important weighting factor in the fusion scheme. Second, the result from the measurement fusion part is reconstructed through a new reconstruction algorithm called self-adaptively modified Landwebber filter. Finally, computer simulation-based experiment is conducted, showing that the novel fusion framework is capable of saving computational resource and enhancing the fusion result and is easy to implement.

关键词： image sampling compressed sensing image reconstruction Computer vision and image processing techniques image and video coding reconstruction algorithm focusing Sensing devices and transducers measurement fusion Transducers and sensing devices sensor fusion self-adaptively modified Landwebber filter multifocus images dual-channel pulse coupled neural network model image fusion framework

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Motion vector generation for video coding by gray prediction

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IET COMPUTER VISION 2011年第1期5卷 14-22页

作者： Wu, Y. -G. Huang, G. -F. Chang Jung Christian Univ Dept Comp Sci & Informat Engn Tainan Taiwan Leader Univ Dept Comp Sci & Informat Engn Tainan Taiwan

An efficient prediction algorithm for motion vectors in video compression is proposed. Motion estimation is an important part in motion compensated video encoding system, which is used to eliminate the temporal redundancy in video sequence. Motion vectors dominate the quality of decoded video so that the generation of motion vectors is an important topic in video coding. Exhaustive block matching algorithm (EBMA) can get the optimal solution for motion vectors, but it takes much computational burden. In the proposed method, the authors use gray prediction to obtain the motion vectors. Gray prediction can predict the motion vectors quickly and accurately. Several video sequences are used to evaluate the performance in this study, and the experimental results show that the time that the proposed method needed is only 1.93% compared to EBMA and 11.75% compared to three steps searching algorithm whereas the degradation of PSNRY compared to EBMA is about 0.43 dB at most, which is almost invisible to human eyes.

关键词： motion vector generation PSNRY image and video coding Algebra EBMA video coding video sequence vectors computational burden video signal processing exhaustive block matching algorithm gray prediction motion estimation

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DC coefficient restoration technique and its application to image coding

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IEE PROCEEDINGS-VISION image AND SIGNAL PROCESSING 2002年第5期149卷 272-282页

作者： Tse, FW Cham, WK Liu, JZ Chinese Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China

In the traditional approach of block transform image coding, a large number of bits are allocated to the DC coefficients. A technique called DC coefficient restoration (DCCR) has been proposed to further improve the compression ability of block transform image coding by not transmitting the DC coefficients but estimating them from the transmitted AC coefficients. images thus generated, however, have inherent errors that degrade the image visual quality. In the paper, a global estimation DCCR scheme is proposed that can eliminate the inherent errors. The scheme estimates all the DC coefficients of the blocks simultaneously by minimising the sum of the energy of all the edge difference vectors of the image. The performance of the global estimation DCCR is evaluated using a mathematical model and experiments. Fast algorithms are also developed for efficient implementation of the proposed scheme.

关键词： mathematical model image visual quality DC coefficient restoration data compression fast algorithms transform coding image restoration transmitted AC coefficients Computer vision and image processing techniques image compression image coding discrete cosine transforms Integral transforms in numerical analysis DCT discrete cosine transform block transform image coding image and video coding global estimation lossy image coding edge difference vectors

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Hardware-software co-design architecture for Joint Photo Expert Graphic XR encoder

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IET image PROCESSING 2012年第9期6卷 1284-1292页

作者： Tseng, C. -F. Lai, Y. -T. Natl Cheng Kung Univ Dept Elect Engn Tainan 701 Taiwan

In recent years, because of to the fast growing of internet and digital multi-media, new image compression algorithms are needed to reduce the transferring bandwidth and the decay of image quality. Joint Photo Expert Graphic (JPEG) extended range (XR) is a new standard for still image compression. Compared to previous standards, it provides better image quality and plentiful pixel format. However, the better image quality often comes with the higher computation complexity. In this study, the authors propose a hardware-software co-design architecture for JPEG XR encoder. For photo overlap transform (POT), and photo core transform (PCT), the complicated parts of JPEG XR, the authors propose new algorithms which eliminate data dependency in the basic filters of POT and PCT so that operations can be executed in parallel. The processing rate of the new algorithms is much faster. The authors also demonstrate a basic filter with multiple functions, which can be time-shared by POT and PCT;the hardware cost can be therefore reduced. Moreover, a memory saving scheme is proposed. Therefore the proposed architecture is suitable for stand-alone application-specific integrated circuit (ASIC). In our co-design, POT and PCT are implemented in hardware and then mapped to field programmable gate array (FPGA), whereas the other procedures of JPEG XR such as quantisation are executed by ARM926-EJ processor. The overall performance of our hardware architecture is 50 fps for 4:4:4 HDTV format at 166 MHz.

关键词： frequency 166 MHz image quality ASIC Filtering methods in signal processing photo core transform ARM926-EJ processor data compression hardware-software codesign digital multimedia image compression algorithm JPEG XR encoder field programmable gate arrays Hardware-software codesign Internet Electronic engineering computing FPGA joint photo expert graphic XR encoder Computer vision and image processing techniques computer architecture image and video coding still image compression application specific integrated circuits image coding hardware architecture photo overlap transform data dependency Integral transforms POT quantisation (signal) Logic circuits Computer architecture computation complexity quantisation JPEG extended range stand-alone application-specific integrated circuit PCT Logic and switching circuits memory saving scheme HDTV format filtering theory filter bandwidth transfer hardware-software co-design architecture field programmable gate array Digital circuit design, modelling and testing transforms

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Analysis of spatial transform motion estimation with overlapped compensation and fractional-pixel accuracy

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IEE PROCEEDINGS-VISION image AND SIGNAL PROCESSING 1999年第6期146卷 339-344页

作者： Lopes, FJP Ghanbari, M Univ Essex Dept Elect Syst Engn Colchester CO4 3SQ Essex England

The authors investigate how the performance of spatial transforms motion estimation can be significantly improved by incorporating overlapped compensation and fractional pixel accuracy. An overlapped spatial transformation (OST) motion model is developed, which successfully addresses the inability of the conventional block matching technique to compensate for complex motion and inside-block motion field discontinuities. Simulation results show that the motion compensated prediction error of this method is reduced by 1.1dB, compared with the conventional overlapped block matching motion estimation, for the same generated motion vectors overhead. To improve the performance, the overlap must be used in both the motion estimation and compensation processes. Further improvement can be obtained using half-pixel precision motion vectors. However, this improvement is comparatively less than the gain of conventional block matching from a half-pixel search.

关键词： prediction theory video coding motion estimation transform coding half-pixel precision motion vectors motion field discontinuities motion compensated prediction error image segmentation motion compensation image matching motion vector overhead video signal processing overlapped compensation Integral transforms in numerical analysis overlapped block matching motion estimation performance overlapped spatial transformation motion model image and video coding fractional-pixel accuracy simulation results spatial transform motion estimation half-pixel search

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Robust discrete wavelet-fan beam transforms-based colour image watermarking

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IET image PROCESSING 2011年第4期5卷 315-322页

作者： Dejey, D. Rajesh, R. S. Manonmaniam Sundaranar Univ Dept Comp Sci & Engn Tirunelveli Tamil Nadu India

Combined discrete wavelet transform-fan beam transform (DWT-FBT) has been explored as a new possible domain for colour image watermarking. The two schemes proposed in the combined domain are (i) wavelet fan beam watermarking on luminance and chrominance and (ii) wavelet fan beam watermarking on chrominance alone. After the application of DWT on the host image and after careful selection of the suitable band of wavelet coefficients for applying FBT, watermarking is done by altering the fan beam transformed coefficients. The schemes proposed achieve a high data embedding capacity in addition to robustness to attacks and produce watermarked images of high quality. Results of the proposed schemes are compared with the two existing DWT-discrete cosine transform watermarking schemes to show its effectiveness.

关键词： luminance discrete wavelet transforms Computer vision and image processing techniques chrominance image and video coding colour image watermarking image coding watermarking Integral transforms robust discrete wavelet-fan beam transforms

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Moving target inverse synthetic aperture radar image resolution enhancement based on two-dimensional block sparse signal reconstruction

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IET image PROCESSING 2021年第13期15卷 3153-3159页

作者： He, Xingyu Tong, Ningning Liu, Tao Air Force Engn Univ Air Traff Control & Nav Coll Xian 710051 Shaanxi Peoples R China Air Force Engn Univ Air & Missile Def Coll Xian Shaanxi Peoples R China Air Force Engn Univ Teaching & Res Guarantee Ctr Xian Shaanxi Peoples R China

To achieve the high-resolution inverse synthetic aperture radar (ISAR) imaging of moving targets, the range Doppler method and compressed sensing technique can be used. However, those methods are generally faced with the problem of migration through range cells and basis mismatch problems, and the imaging results can be improved. To solve these problems and improve the image quality, the problem of ISAR imaging is termed as a block-sparse signal recovery problem by utilizing the block-sparse structure of the ISAR images. A localized low-rank promoting (LLP) method is introduced and extended to the complex case for the recovery of range compressed block-sparse signals. The sparse recovery problem is solved by minimizing another function, which is the surrogate function that can be solved more effectively. Based on the LLP method, the coefficients of the range compressed echo signal are reconstructed and some 2 x 2 matrices can be obtained. And then the log-determinant function is introduced to find the low rankness solutions for these matrices. Then the LLP method is also used in the cross-range domain to reconstruct the ISAR image. Experimental results show that the proposed method can recover better focused and higher quality ISAR images compared with the traditional methods.

关键词： image resolution range compressed echo signal range compressed block-sparse signals compressed sensing Radar equipment, systems and applications image quality LLP method two-dimensional block sparse signal reconstruction image enhancement Optimisation techniques ISAR imaging range Doppler method image and video coding high-resolution inverse synthetic aperture radar imaging sparse recovery problem higher quality ISAR images moving targets range cells block-sparse signal recovery problem matrix algebra Interpolation and function approximation (numerical analysis) ISAR image block-sparse structure synthetic aperture radar radar imaging target inverse synthetic aperture radar image resolution enhancement basis mismatch problems cross-range domain localized low-rank promoting method

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Advanced fine-tuning procedures to enhance DNN robustness in visual coding for machines

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EURASIP JOURNAL ON image AND video PROCESSING 2024年第1期2024卷 1-23页

作者： Marie, Alban Desnos, Karol Mercat, Alexandre Morin, Luce Vanne, Jarno Zhang, Lu Tampere Univ Ultra Video Grp Tampere Finland Univ Rennes INSA Rennes CNRS IETRUMR 6164 Rennes France

video coding for Machines (VCM) is gaining momentum in applications like autonomous driving, industry manufacturing, and surveillance, where the robustness of machine learning algorithms against coding artifacts is one of the key success factors. This work complements the MPEG/JVET standardization efforts in improving the resilience of deep neural network (DNN)-based machine models against such coding artifacts by proposing the following three advanced fine-tuning procedures for their training: (1) the progressive increase of the distortion strength as the training proceeds;(2) the incorporation of a regularization term in the original loss function to minimize the distance between predictions on compressed and original content;and (3) a joint training procedure that combines the proposed two approaches. These proposals were evaluated against a conventional fine-tuning anchor on two different machine tasks and datasets: image classification on imageNet and semantic segmentation on Cityscapes. Our joint training procedure is shown to reduce the training time in both cases and still obtain a 2.4% coding gain in image classification and 7.4% in semantic segmentation, whereas a slight increase in training time can bring up to 9.4% better coding efficiency for the segmentation. All these coding gains are obtained without any additional inference or encoding time. As these advanced fine-tuning procedures are standard-compliant, they offer the potential to have a significant impact on visual coding for machine applications.

关键词： video coding for Machines (VCM) coding artifacts image and video coding Deep neural network (DNN) Deep learning Fine-tuning

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