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hybrid image-coding SCHEME INCORPORATING HUMAN VISUAL-SYSTEM CHARACTERISTICS

OPTICAL ENGINEERING 1991年第7期30卷 940-946页

作者： NGAN, KN KOH, HC WONG, WC NGEE ANN POLYTECH DEPT ELECTR ENGNSINGAPORESINGAPORE

In this paper, a hybrid image coding scheme combining the advantages of both classified vector quantization (CVQ) and discrete cosine transform (DCT) is proposed. An image vector is classified according to its content activity. Vectors of low activity (shade vectors) are coded using CVQ. For vectors of high activity (edge vectors), DCT is used. To enhance the visual quality of the decoded image, the modulation transfer function (MTF) of the human visual system (HVS) model is incorporated into the DCT coding algorithm. Simulation results showed that the proposed approach allowed good subjective image quality to be obtained at relatively low bit rates. The improvement in quality is even more pronounced at low bit rates, if this scheme is compared to those schemes employing CVQ or DCT alone.

关键词： VISUAL COMMUNICATIONS hybrid image coding CLASSIFIED VECTOR QUANTIZATION DISCRETE COSINE TRANSFORM

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hybrid image coding for real-time computer screen video transmission

Hybrid image coding for real-time computer screen video tran...

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Conference on Visual Communications and image Processing 2004

作者： Lin, T Hao, PW Xu, C Feng, JF Peking Univ Natl Lab Machine Percept Beijing 100871 Peoples R China

ISBN: (纸本)0819452114

In this paper, we present a novel hybrid image coding scheme for real-time applications of computer screen video transmission. Based on the Mixed Raster Content (MRC) multilayer imaging model, the background picture is compressed with lossy JPEG, and the foreground layer consisting of text and graphics is compressed with a block-based lossless coding algorithm, which integrates shape-based coding, palette-based coding, palette reuse, and LZW algorithm. The key technique is to extract text and graphics from background pictures accurately and with low complexity. Shape primitives, such as lines, rectangles, and isolated pixels with prominent colors, are found to be significant clues for textual and graphical contents. The shape-based coding in our lossless algorithm provides intelligence to extract the computer-generated text and graphics elegantly and easily. Experimental results demonstrate the efficiency and low complexity of our proposed hybrid image coding scheme.

关键词： hybrid image coding shape-based coding palette-based coding mixed raster content content adaptivity

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A hybrid image coding ALGORITHEM

A HYBRID IMAGE CODING ALGORITHEM

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International Conference on Communication Technology(ICCT’94)

作者： Liu Qi Han ChengDe Institude of Computing Technology Academia Sinica

In this paper,a hybrid image coding algorithm combining the advantages of both classified vector quantization(CVQ) and discrete cosine transform(DCW) is *** image vector is classified according to its content *** of low activity(shade vectors) are coded using *** vectors of high activity(edge vectors),DCT is *** enhence the visual quality of the decoded image,the modulation transfer function(MTF) of the human visual system(HVS) model is incorporated into the DCT coding *** results showed that the proposed approach allowed good subjective image quality to be obtained at relatively low bit rates,The improvement in quality is even more pronounced at low bit rates,if this algorithm is compared to those algorithm employing CVQ or DCT alone.

关键词： visual communication hybrid image coding classified vector quantization discrete cosine transform

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EFFICIENT coding OF SIDE INFORMATION IN A LOW BITRATE hybrid image CODER

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SIGNAL PROCESSING 1990年第1期19卷 61-73页

作者： SCHILLER, H CHAUDHURI, BB Institut für Theoretische Nachrichtentechnik Universität Hannover Appelstrasse 9a 3000 Hannover 1 Fed. Rep. Germany

With a hybrid coding scheme intended for the transmission of video sequences at 64 kbit/s, several ways of reducing side information are investigated. In a first step, a dual blocksize (DB) concept is introduced to improve the coding efficiency of the side information and visual appearance of the transmitted pictures. In a second step, a hierarchical blockmatching algorithm for improved motion estimation is employed and the motion vector components are differentially coded using variable word length (VWL) codes. The interfield correlations between predictor modes as well as spatial correlations between scan lengths are investigated for a more efficient coding of other side information items. Simulation results on CCITT video test sequences are presented. Bei einem hybrid-Codiersystem für eine Übertragung von Videosequenzen bei 64 kbit/s werden verschiedene Verfahren zur Reduktion der Seiteninformationen untersucht. Im ersten Schritt wird die gleichzeitige Verwendung von 2 Blockgrößen eingeführt, was den Umfang der anfallenden Seiteninformation prinzipiell verringert und dadurch die Bildqualität verbessert. Im zweiten Schritt wird ein hierarchisches Blockmatching-Verfahren für verbesserte Bewegungsschätzung verwendet. Die damit gewonnenen Bewegungsvektoren können differentiell Huffman-codiert werden, wodurch sich der Übertragungsaufwand für die Vektor-Seiteninformation ca. halbiert. Für eine effiziente Übertragung der verbleibenden Seiteninformationen werden die Korrelationen der Prädiktor-Betriebsarten aufeinanderfolgender Bilder sowie die örtllichen Korrelationen der EOB-Seiteninformation benachbarter Sub-Blöcke untersucht. Simulationsergebnisse mit CCITT Standard-Testsequenzen werden präsentiert. Plusieurs méthodes de réduction de l'information de service sont étudiées dans le contexte d'un système de codage hybride pour la transmission de séquences vidéo à 64 kbit/s. Dans un premier temps, le concept de taille de bloc à deux valeurs (en anglais: dual blocksize, D

关键词： hybrid image coding 64 kbit/s video transmission dual blocksize side information motion vector coding predictor mode coding EOB coding

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Fast fractal coding of subbands using a non-iterative block clustering

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JOURNAL OF VISUAL COMMUNICATION AND image REPRESENTATION 2005年第1期16卷 55-67页

作者： Belloulata, K Univ Sherbrooke Dept Genie Elect & Genie Informat Sherbrooke PQ J1K 2R1 Canada

We propose a new image coding scheme which uses a fast non-iterative algorithm for block clustering in fractal coding of wavelet transform coefficients. The original image is first decomposed into subbands containing information in different spatial directions and different scales, using an orthogonal wavelet filter bank. Subbands are encoded using local iterated function systems (LIFS) with range and domain blocks presenting horizontal or vertical directionalities. Their sizes are adapted to the correlation lengths and the resolution of each subband. This hybrid compression scheme allows to use the natural classification obtained by using a subband decomposition and reduce the computational complexity by a 12:1 factor. In order to increase this speedup, we propose a fast non-iterative algorithm for block clustering which classifies the directional domain and range blocks and leads to an accelerated LIFS generation in each subband. The proposed approach reduces the computational complexity of the basic fractal compression algorithm by a 50:1 factor and gives better PSNR/bit rate results, especially for images presenting directionalities. (C) 2004 Elsevier Inc. All rights reserved.

关键词： fractal coding hybrid image coding hybrid subband/fractal coding clustering

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Fractal coding of subbands with an oriented partition

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SIGNAL PROCESSING-image COMMUNICATION 1998年第3期12卷 243-252页

作者： Belloulata, K Baskurt, A Benoit-Cattin, H Prost, R INSA 502 CREATIS F-69621 Villeurbanne France

We propose a new image compression scheme based on fractal coding of the coefficients of a wavelet transform, in order to take into account the self-similarity observed in each subband. The original image is first decomposed into subbands containing information in different spatial directions and at different scales, using an orthogonal wavelet-generated filter bank. Subbands are encoded using local iterated function systems (LIFS), with range and domain blocks presenting horizontal or vertical directionalities. Their sizes are defined according to the correlation lengths and resolution of each subband. The edge degradation and the blocking effects encountered at low bit-rates using conventional LIES algorithm are reduced with this approach. The computation complexity is also greatly decreased by a 12:1 factor in comparison to fractal coding of the full resolution image. The proposed method is applied to standard test images. The comparison with other fractal coding approaches and with JPEG shows an important increase in terms of PPSNR/bit-rate. Especially for images presenting a privileged directionality, the use of adaptive partitions results in about 3 dB improvement in PPSNR. We also discuss the distorsion versus rate improvement obtained on high-frequency subbands when fractal coding instead of pyramidal vector quantization is used. Our approach achieves a real gain in PPSNR for low bit-rates between 0.3 and 1.2 bpp. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： fractal coding hybrid image coding hybrid subband/fractal coding

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PPT image Segmentation Based on Color Entropy 14

PPT Image Segmentation Based on Color Entropy

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Joint 14th IEEE Int Conf on Trust, Secur and Privacy in Comp and Commun / 13th IEEE Int Symposium on Parallel and Distributed Proc with Applications / 9th IEEE Int Conf on Big Data Science and Engineering (IEEE TrustCom-ISPA-BigDataSE)

作者： He, Feijuan Chen, Xuelu Xu, Dawei Miao, Xianglin Xi An Jiao Tong Univ City Coll Dept Comp Sci Xian 710018 Peoples R China Xi An Jiao Tong Univ Dept Comp Sci MOEKLINNS Lab Xian Peoples R China

ISBN: (纸本)9781467379526

image segmentation is a preliminary requirement to hybrid image encoding. In this paper, we propose SIG, an algorithm based on information gain for slide image segmentation. SIG algorithm depends on two features observed from the slide image samples: color entropy distribution and information gain. SIG algorithm consists of two stages. First, it finds the seed of monochrome, textual and grayscale images following the greedy strategy, and then it expands the seed image to generate image blocks seeking maximum information gain. Empirical experiments indicate that SIG-based hybrid image encoding is superior to JPEG2000 as well as 8x8 and 16x16 block-based hybrid image encoding in terms of efficiency.

关键词： image Segmentation Information Gain Color Entropy Slide hybrid image coding

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A hybrid SPIHT-EBC image coder

A hybrid SPIHT-EBC image coder

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International Multiconference of Engineers and Computer Scientists

作者： Hsin, Hsi-Chin Lien, Jenn-Jier Sung, Tze-Yun Department of Computer Science and Information Engineering National Formosa University Taiwan Department of Computer Science and Information Engineering National Cheng Kung University Taiwan Department of Microelectronics Engineering Chung Hua University Taiwan

ISBN: (纸本)9789889867140

For images with textures, the high frequency wavelet coefficients are likely to become significant after few coding passes of the set partitioning in hierarchical trees (SPIHT) algorithm, which degrades substantially the coding performance. A hybrid image coder using SPIHT and embedded block coding (EBC) is thus proposed. In which, wavelet coefficients of the low frequency subbands representing the low frequency components of images are still coded by using SPIHT;wavelet coefficients of the high frequency subbands most likely representing the high-detail textures are coded by using EBC. The intermediate coding results of SPIHT can be used as estimates to facilitate the coding operations of EBC, which takes both of the well defined hierarchical tree structure across wavelet subbands and energy clustering within each subband into account to improve the compression performance. Experimental results show that EBC outperforms SPIHT for coding images at middle-high rates of bits per pixel, whereas SPIHT is preferable to EBC at low rates of bits per pixel. As expected, the hybrid SPIHT-EBC coder is comparable with SPIHT and EBC at low and middle-high rates of bits per pixel, respectively, which demonstrates the overall coding performance. can be improved by using the proposed hybrid coder.

关键词： embedded block coding hybrid image coding SPIHT wavelet transform

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