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Reduction of blocking artifact based on edge information in discrete cosine transform-coded images

OPTICAL ENGINEERING 2011年第9期50卷 097403-097403页

作者： Kwon, Goo-Rak Lama, Ramesh Kumar Pyun, Jae-Young Lee, Sang-Woong Chosun Univ Dept Informat & Commun Engn Kwangju 501759 Chonranam Do South Korea Chosun Univ Dept Comp Engn Kwangju 501759 Chonranam Do South Korea

We propose new method for the reduction of blocking artifacts present in low bit-rate coded images. This algorithm performs the deblocking operation in two modes that are determined by the number of edge pixels around the block boundary. The number of edge pixels is calculated by applying the Roberts edge filter. An appropriate filtering operation is performed for each mode in both the horizontal and vertical directions. First, when the mode is associated with a smooth region, a strong filtering operation is applied because flat regions are more sensitive to the human visual system. In the second mode, an adaptive low-pass filter that is based on pixel behavior around the block boundaries is applied. This filter reduces the blocking artifact without introducing undesired blurring effects, while the original image edge is preserved. Although the proposed approach is simple and operates in the spatial domain, experimental results show that it improves both the subjective and objective qualities of the coded image with various features. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3625424]

关键词： deblocking blocking artifacts block-based coding

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Reduction of blocking artifacts for HDTV using offset-and-shift technique

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 2007年第4期53卷 1736-1743页

作者： Kim, Jongho Choi, Minseok Jeong, Jechang Hanyang Univ Dept Elect & Comp Engn Seoul 133791 South Korea

This paper addresses an effective post-processing technique to remove blocking artifacts, which severely degrade visual quality in block-based image coding. The proposed algorithm classifies blocks into four types based on directional activity and removes the blocking artifacts while preserving edges and texture information by applying different types and strength of filter for each block type. Moreover, the proposed scheme includes a two-dimensional filtering method in order to remove staircase noises and corner outliers around diagonal and curved edges. Experimental results show that the proposed algorithm outperforms a number of deblocking methods in the literature in terms of PSNR and subjective visual quality. Furthermore, the execution time of the proposed algorithm takes less than that of the other methods, and thus it can be incorporated into real-time applications for moving pictures as well as still images.

关键词： deblocking post-processing offset-and-shift technique blocking artifact block-based coding

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Detection method and removing filter for corner outliers in highly compressed video

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1st Pacific Rim Symposium on Image and Video Technology (PRSIVT 2006)

作者： Kim, Jongho Jeon, Kicheol Jeong, Jechang Hanyang Univ Dept Elect & Comp Engn 17 Haengdang Seoul 133791 South Korea

ISBN: (纸本)9783540682974

We propose a detection method and a removal filter for corner outliers in order to improve visual quality in highly compressed video. Corner outliers are detected using the direction of edge going through a block-corner and the properties of blocks around the block-corner. The proposed filter for removing corner outliers, which compensates the stair-shaped discontinuities around edges using the adjacent pixels, is applied to the detected area. Simulation results show that the proposed method improves, particularly in combination with deblocking filters, the visual quality remarkably.

关键词： corner outlier low bit-rate video block-based coding MPEG-4 video

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Adaptive deblocking filter

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2003年第7期13卷 614-619页

作者： List, P Joch, A Lainema, J Bjontegaard, G Karczewicz, M Deutsch Telekom T Syst D-64295 Darmstadt Germany UB Video Inc Vancouver BC V6B 2R9 Canada Nokia Res Ctr Irving TX 75039 USA TANDBERG N-1324 Lysaker Norway

This paper describes the adaptive deblocking filter used in the H.264/MPEG-4 AVC video coding standard. The filter performs simple operations to detect. and analyze artifacts on coded block boundaries and. attenuates ... 详细信息

关键词： block-based coding video coding video filtering video signal processing

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Adaptive image compression using local pattern information

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PATTERN RECOGNITION LETTERS 2002年第14期23卷 1837-1845页

作者： Pan, F Nanyang Technol Univ Ctr Signal Proc Sch EEE Singapore 639798 Singapore

This paper describes a new adaptive coding technique to the coding of transform coefficients used in block based image compression schemes. The presence and orientation of the edge information in a sub-block are used to select different quantization tables and zigzag scan paths to cater for the local image pattern. Measures of the edge presence and edge orientation in a sub-block are calculated out of their DCT coefficients, and each sub-block can be classified into four different edge patterns. Experimental results show that compared to JPEG and the improved HVS-based coding, the new scheme has significantly increased the compression ratio without sacrificing the reconstructed image quality. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： image compression JPEG block-based coding adaptive quantization

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Efficient block-based coding of noisy images by combining pre-filtering and DCT

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ELECTRONICS LETTERS 1999年第20期35卷 1717-1719页

作者： Kim, SD Jang, SK Kim, MJ Ra, JB Korea Adv Inst Sci & Technol Dept Elect Engn Yusong Gu Taejon 305701 South Korea

An efficient block-based coding scheme for noisy images is proposed. Unlike a conventional encoder where pre-filtering, discrete cosine transforms (DCT), quantisation, and variable length coding (VLC) are cascaded, the proposed image coder has only a modified DCT and a VLC, and performs pre-filtering and quantisation simultaneously in the modified DCT operation.

关键词： block-based coding VLC discrete cosine transforms pre-filtering Integral transforms in numerical analysis Image and video coding DCT noisy images image coding Codes quantisation (signal) variable length coding quantisation Signal processing theory variable length codes Computer vision and image processing techniques Image recognition block codes

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A deblocking filter with two separate modes in block-based video coding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1999年第1期9卷 156-160页

作者： Kim, SD Yi, J Kim, HM Ra, JB Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea LG Semicon Co Ltd Seoul South Korea

This paper presents a method to remove blocking artifacts in low bit-rate block-based video coding. The proposed algorithm has two separate filtering modes, which are selected by pixel behavior around the block boundary, In each mode, proper one-dimensional filtering operations are performed across the block boundary along the horizontal and vertical directions, respectively. In the first mode, corresponding to Bat regions, a strong filter is applied inside the block as well as on the block boundary because the Bat regions are more sensitive to the human visual system (HVS) and the artifacts propagated from the previous frame due to motion compensation are distributed inside the block. In the second mode, corresponding to other regions, a sophisticated smoothing filter, which is based on the frequency information around block boundaries, is used to reduce blocking artifacts adaptively without introducing undesired blur. Even though the proposed deblocking filter is quite simple, it improves both subjective and objective image quality for various image features.

关键词： block-based coding blocking artifacts deblocking postprocessing technique

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Design of wavelet-based image codec in memory-constrained environment

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2001年第5期11卷 642-650页

作者： Bao, YL Kuo, CCY Univ So Calif Integrated Multimedia Syst Ctr Los Angeles CA 90089 USA Univ So Calif Dept Elect Engn Syst Los Angeles CA 90089 USA

This work presents a high-performance wavelet transform based image coder that is designed for image compression in a system with limited resources. In this image coder the dual-sliding wavelet transform (DSWT) is first applied to image data to generate wavelet coefficients in fixed-size blocks. Here, a block consists of wavelet coefficients only from a single subband. Then, the resulting coefficient blocks are directly coded with the Low-Complexity Binary Description (LCBiD) coefficient coding algorithm. No parent-child relationship is exploited in the coding process. There is no intermediate buffering needed between DSWT and LCBiD. The compressed bit stream generated by the proposed coder is both SNR and resolution scalable, as well as highly resilient to transmission errors. Both DSWT and LCBiD process the data in blocks whose size is independent of the size of the input image. This gives more flexibility in its implementation. The codec has a very good coding performance even the size of a coefficient block is as small as (16,16).

关键词： block-based coding block-based transform image compression low complexity compression wavelet transform

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A practical postprocessing technique for real-time block-based coding system

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1998年第1期8卷 4-8页

作者： Chan, YH Hong, SW Siu, WC Hong Kong Polytech Univ Dept Elect Engn Kowloon Hong Kong

In this paper, a noniterative postprocessing method is proposed to restore the images encoded with block-based compression standards such as Joint Photographic Experts Group (JPEG). This method classifies small local boundary regions according to their intensity distribution and then selects appropriate linear predictors to estimate the corresponding boundary pixels in the regions. This approach is easy to implement and we found in our simulations that its restoration performance was very respectable compared with the reported postprocessing methods.

关键词： block-based coding codec deblocking image restoration JPEG postprocessing technique vector quantization

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DCT information recovery of erroneous image blocks by a neural predictor

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2000年第6期18卷 1111-1121页

作者： De Natale, FGB Perra, C Vernazza, G Univ Trent DICA I-38050 Trent Italy Univ Cagliari DIEE I-09123 Cagliari Italy Univ Genoa DIBE I-16145 Genoa Italy

In this paper, the problem of DCT information recovery in the transmission of coded visual data over packet networks is addressed. The loss of a packet conveying coded block data leads to the unsuccessful reconstruction of the relevant area, with consequent degradation of the received image quality. The proposed method allows recovery of a subset of the missing DCT coefficients sufficient to achieve good reconstruction quality of the lost block, based on the available surrounding information. To this purpose, a neural predictor was carefully designed and suitably trained with an appropriate set of synthetic and natural patterns. An extensive testing phase, performed on a large set of images with different frequency characteristics, revealed that the method provides very good reconstruction capabilities.

关键词： block-based coding error concealment neural prediction

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