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ADAPTIVE transform TREE coding OF IMAGES

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1992年第5期10卷 902-912页

作者： PEARLMAN, WA JAKATDAR, P LEUNG, MM NYNEX CORP WHITE PLAINSNY 10604 ANAL SCI CORP READINGMA 01867

A tree code, asymptotically optimal for stationary Gaussian sources and squared error distortion [1], is applied suboptimally to encode the discrete cosine transform (DCT) of image subblocks. The variance spectrum of each block DCT is estimated and specified uniquely by a set of one-dimensional autoregressive parameters. The average pel rate for each block is allowed to vary to meet the specification of the same average distortion per block. Since the variance spectrum and rate are different for every block, so is the code tree. First, a level of search intensity is determined through simulation where tree coding outperforms in mean squared error a comparable coding simulation with quantization replacing tree coding. Then, a secondary coding step (postcoding) is introduced to encode, with insignificant additional rate, the large isolated errors which may result from the tree search. Comparative coding simulations with a 256 x 256 and 512 x 512 image show that DCT tree coding with postcoding is clearly superior to DCT quantization and that a variable block rate assignment gains about 3 dB over a fixed block rate assignment. The mean squared error results achieved for the tree coding system are comparable to or surpass all previous results reported for the same images.

关键词： Image coding Discrete cosine transforms Acoustic distortion Quantization Discrete transforms transform coding Gain Image segmentation Encoding Research and development

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CHANNEL ERROR RECOVERY FOR transform IMAGE-coding

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IEEE TRANSACTIONS ON COMMUNICATIONS 1981年第12期29卷 1754-1762页

作者： MITCHELL, OR TABATABAI, AJ School of Electrical Engineering Purdue University West Lafayette IN USA Bell Laboratories Holmdel NJ USA

A method is presented to automatically inspect the block boundaries of a reconstructed two-dimensional transform coded image, to locate blocks which are most likely to contain errors, to approximate the size and type of error in the block, and to eliminate this estimated error from the picture. This method uses redundancy in the source data to provide channel error correction. No additional channel error protection bits or changes to the transmitter are required. It can be used when channel errors are unexpected prior to reception.

关键词： Image coding Protection Image reconstruction transform coding Pixel Bit rate Humans Redundancy Error correction Transmitters

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APPROACHES TO ADAPTIVE transform SPEECH coding AT LOW BIT RATES

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND SIGNAL PROCESSING 1979年第1期27卷 89-95页

作者： ZELINSKI, R NOLL, P UNIV BREMEN BREMENFED REP GER

This paper discusses problems of adaptive transform coding schemes at bit rates of 12 kbit/s and below. Objective and subjective performance reductions, like low-pass filtering effects as one of the main sources of perceptual distortion, are investigated and proposals are made how to improve the performance of the coder at low and medium bit rates. Additionally, the needed transmission of side information reduces the efficiency of the scheme. Various methods to lower the rate of this supplementary data signal are given as well as modifications of the scheme which lead to a more easily implemented coder structure.

关键词： Speech coding Bit rate transform coding Proposals Discrete cosine transforms Discrete transforms Low pass filters Filtering Quantization Decoding

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PERFORMANCE OF transform AND SUBBAND coding SYSTEMS COMBINED WITH HARMONIC SCALING OF SPEECH

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND SIGNAL PROCESSING 1981年第2期29卷 273-283页

作者： MALAH, D CROCHIERE, RE COX, RV Department of Electrical Engineering Technion-Israel Institute of Technology Haifa Israel Department of Acoustics Research Bell Laboratories Inc. Murray Hill NJ USA

In this study an approach for improving the performance of waveform coders, based on coding a frequency scaled speech signal, is examined and subjectively evaluated for specific subband and transform coding systems. The recently developed simple and efficient time-domain harmonic scaling (TDHS) algorithms are used to frequency scale the speech signal. The underlying frequency-domain model of the pitch-adaptive TDHS algorithms provides insight and guidelines for their use in this application, as outlined in this work. The subjective evaluation is based on an A-B comparison test involving 12 listeners and shows a meaningful improvement in quality for the waveform coders used at low bit rates. In particular, subband coding (SBC) combined with TDHS (SBC/HS) at 9.6 kbits/s was found to provide a quality equivalent to that of SBC alone at 16 kbits/s, i.e., a bit-rate advantage of about 7 kbits/s was realized. For the speech specific adaptive transform coder (ATC) used, the combined system (ATC/HS) achieves a bit-rate advantage of 4 kbits/s at 7.2 kbits/s. The SBC/HS system emerges as a particularly attractive method for speech encoding at the data rate of 9.6 kbits/s since its quality is comparable to that of ATC/HS (or SBC at 16 kbits/s). Yet, its complexity is lower than ATC and the system is amenable to real-time hardware implementation using current technology.

关键词： Speech coding Frequency Speech analysis transform coding Time domain analysis Guidelines Testing Bit rate Encoding Real time systems

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Image Compression Performance of HEVC Intra Prediction with Different transform Coefficient coding Methods 26

Image Compression Performance of HEVC Intra Prediction with ...

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26th IEEE Signal Processing and Communications Applications Conference (SIU)

作者： Cekli, Serap Akman, Ali Maltepe Univ Bilgisayar Muhendisligi Bolumu Istanbul Turkey

ISBN: (纸本)9781538615010

HEVC is the new coding standard providing higher compression ratios with comparated to the other existent coding standards. In this study, the image compression performance using intra prediction is examined. Especially, the coding of transformation of prediction errors are handled and three different coding structure is proposed. The compression code efficiency is obtained for different block sizes and image sizes by depending on the transform coding formats. The original images are recovered by decoding codes of the compressed images, and the similarity with the original images is inspected by consideirng the PSNR values.

关键词： HEVC intra-prediction image compression transform coding

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PRE-ECHO REDUCTION IN transform AUDIO coding VIA TEMPORAL ENVELOPE CONTROL WITH MACHINE LEARNING BASED ESTIMATION 49

PRE-ECHO REDUCTION IN TRANSFORM AUDIO CODING VIA TEMPORAL EN...

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49th IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Kim, Jae-Won Jo, Byeongho Beack, Seungkwon Park, Hochong Kwangwoon Univ Seoul South Korea ETRI Daejeon South Korea

ISBN: (纸本)9798350344868;9798350344851

This paper proposes a new method for pre-echo reduction in transform-based audio coding by controlling the temporal envelope of the waveform. The proposed method comprises two operating modes: temporal envelope flattening and temporal envelope correction of a target signal. The proposed method estimates signal levels with a low temporal resolution from side information using machine learning and converts them into a signal to be applied to the target signal to flatten and correct the temporal envelope. It also adjusts the signals to maintain signal continuity between the non-transient and transient frames. The proposed method differs from conventional methods in that it directly modifies the waveform before encoding and after decoding, which makes it useful as a new coding tool for legacy codecs. A subjective performance evaluation confirms that the proposed method uses fewer bits to provide sound quality equivalent to that of the short-window transform.

关键词： audio coding machine learning pre-echo temporal envelope transform coding

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Improving the Compression Efficiency for transform Video coding 4

Improving the Compression Efficiency for Transform Video Cod...

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4th International Conference on Systems and Informatics (ICSAI)

作者： Lin, Jianyu Shantou Univ Dept Elect Engn Guangdong Prov Key Lab Digital Signal & Image Pro Shantou Guangdong Peoples R China

ISBN: (纸本)9781538611074

A new 3D transform video coding algorithm is introduced, which does not use motion compensation. More independent and highly efficient algorithms are employed for each key step of the transform coding. For the transform step, the SCWP (Spectral Condensed Wavelet Packet) is adopted. For the quantization step, a trimming process is implemented, which keeps the bit allocation function of the significant propagation technique but is independent from the entropy coding step. For the entropy coding step, a novel entropy coding technique based upon binary run-length coding is proposed. This binary entropy coding can be applied to multiple symbol source coding, and it approaches an optimal efficiency bound which is within 1.5% of the source entropy when the source approaches iid. Principally, the complexity of the proposed transform video coding algorithm is comparable to that of a 2D still image transform coding algorithm. However, its compression performance is competitive to HEVC at high compression bitrates.

关键词： transform coding video compression lossless entropy coding

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transform audio coding with arithmetic-coded scalar quantization and model-based bit allocation

Transform audio coding with arithmetic-coded scalar quantiza...

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32nd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Oger, Marie Ragot, Stephane Antonini, Marc France Telecom R&D TECH SSTP Av Pierre Marzin F-22307 Lannion France Univ Nice Sophia Antipolis F-06903 Sophia Antipolis France CNRS UMR 6070 Lab I3S F-06903 Sophia Antipolis France

ISBN: (纸本)1424407281

In this paper we present a new model-based method to code the transform coefficients of audio signals. The histogram of transform coefficients is approximated by a generalized Gaussian model for efficient model-based bit allocation and the spectrum is coded by scalar quantization followed by arithmetic coding. An example coder operating at 16 kHz and using predictive modified discrete cosine transform (MDCT) coding is described. We compare the performance of the proposed coder with ITU-T G.722.1. Objective and subjective quality results are presented. The proposed coder is better than ITU-T G.722.1 at 24 kbit/s and equivalent at 32 kbit/s.

关键词： transform coding audio coding modeling

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A LEVEL-MAP APPROACH TO transform COEFFICIENT coding 24

A LEVEL-MAP APPROACH TO TRANSFORM COEFFICIENT CODING

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24th IEEE International Conference on Image Processing (ICIP)

作者： Han, Jingning Chiang, Ching-Han Xu, Yaowu Google Inc WebM Codec Team 1600 Amphitheatre Pkwy Mountain View CA 94043 USA

ISBN: (纸本)9781509021758

transform coding is widely used in the video and image codec to largely remove the spatial correlation. The magnitude of transform coefficient is weakly correlated to a number of factors, including its frequency band, the neighboring coefficient magnitudes, luma/chroma planes, etc. To exploit such correlations for efficient entropy coding, one would build a probability model conditioned on the available contexts. However, the interaction of these factors creates a high dimensional space, a direct use of which would easily fall into the over-fitting problem. How to construct a compact context set which effectively captures the underlying correlations remains a major challenge in video and image compression. Prior research work primarily relies on bucketizing the previously coded coefficients into a small number of categories as the context model for next coefficient. Certain information loss is inevitable due to the classification process. To fully exploit the available context in a limited model space, a level map approach is proposed in this work. It decomposes the coding of coefficient magnitudes into consecutive runs of binary map coding, each corresponds to whether a coefficient is equal to or greater than the given level. Under the Markov assumption across the levels, nearly all the reference symbols available to each level map can be approximated as binary random variables. It hence allows the context model to account for all the surrounding coefficients information provided by the lower level maps, while retaining a reasonably compact size. Experimental evidence demonstrates that the proposed coding scheme provides considerable compression performance gains consistently over a large test settings.

关键词： transform coding probability context modeling level map adaptive coefficient scan

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ONE-DIMENSIONAL DIRECTIONAL UNIFIED transform FOR INTRA coding

ONE-DIMENSIONAL DIRECTIONAL UNIFIED TRANSFORM FOR INTRA CODI...

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18th IEEE International Conference on Image Processing (ICIP)

作者： Yamaguchi, Jun Shiodera, Taichiro Asaka, Saori Tanizawa, Akiyuki Yamakage, Tomoo Toshiba Co Ltd Corp Res & Dev Ctr Tokyo Japan

ISBN: (纸本)9781457713033

In this paper, we present the One-Dimensional Directional Unified transform (1DDUT) for intra coding. Intra prediction in H.264/AVC has eight different directional prediction modes and a DC prediction mode. Since the statistical characteristics of prediction residuals are different in each prediction mode, coding efficiency can be improved by applying the different optimal transform for each prediction mode. However, in order to avoid the increase of the complexity, unification of the transforms is desired. Therefore we classify the characteristics of the prediction residuals along the vertical or the horizontal direction, where each direction has two classes and their characteristics are similar to each other between directions. It is sufficient to use two kinds of 1-D transforms that are designed based on the unified characteristics. One is the well-known Discrete Cosine transform, and the other is a predetermined 1-D transform based on the Karhunen-Loeve transform method. 1DDUT switches DCT and the predetermined 1-D transform according to the intra prediction modes. 1DDUT can achieve 8.71% bitrate reduction on average with negligible complexity increase compared to the DCT-like transform used in H.264/AVC.

关键词： Video coding transform coding Discrete cosine transforms Karhunen-Loeve transforms

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