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A novel detection and recovery system for tampered images using block truncation coding and vector quantization

The Journal of Photographic Science 2003年第4期51卷 235-246页

In this paper, a novel detection and recovery system is proposed for image authentication based on two compression schemes: block truncation coding and vector quantization. In order to reduce the overhead in the communication, the sender first compresses an image and then refines the characteristic values from the compressed image. The characteristic values are encrypted to digital signatures using the RSA scheme (proposed by Rivest, Shamir and Adleman). The signatures are embedded into the compressed image and thus the image integrity can be authenticated after transmission. Upon receipt of the compressed image, the receiver extracts the signatures and then decrypts the characteristic values using the sender's public key. Another characteristic value can also be decoded by the image compression scheme. By comparing a few characteristic values, the system determines whether or not the decompressed image is tampered and then outputs a correct characteristic value to rebuild the tampered regions. Furthermore, the proposed scheme authenticates the integrity of the image to the receiver and effectively recovers the tampered image.

关键词： block truncation coding vector quantization image authentication RSA digital signature

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A novel image coding method based on hybrid fractal

A novel image coding method based on hybrid fractal

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6th World Congress on Intelligent Control and Automation

作者： Sun, Yuge Zhao, Lihong Wang, Yongjun Xu, Xinhe Northeastern Univ Informat Sci & Engn Coll Shenyang 110004 Liaoning Prov Peoples R China

ISBN: (纸本)1424403316

In this paper we present a novel image coding method, which adopts a nonlinear model based on hybrid fractal. we generalize 64 kinds of geometry transformations based on it. The process of selecting Domain block and transforming modes is speeded up by defining eigenvalues. Based on the rapid matching strategy of Range block's Neighborhood, non-matching blocks are coded by truncation coding, and smooth blocks are coded by average coding and three-level qua-tree coding scheme. The compression performance of this method is excellent, especially in coding time.

关键词： nonlinear model fractal block coding block truncation coding range block's neighborhood

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Fuzzy block truncation coding

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OPTICAL ENGINEERING 2002年第12期41卷 3161-3167页

作者： Boudraa, AO Beghdadi, A Dehalk, SMR Iordache, R Ecole Navale IRENav F-29200 Brest France Univ Paris 13 F-93430 Villetaneuse France ENST Dept Image F-75634 Paris France Tampere Univ Technol Inst Signal Proc FIN-33101 Tampere Finland

block truncation coding (BTC) is a well known lossy compression scheme. Due to its low complexity and easy implementation, BTC has gained wide interest in its further development and application for image compression. Based on simple thresholding, BTC retains sharp edges and thus leads to artifacts such as the staircase effect. The second problem encountered in BTC is the splitting of homogeneous regions, which produces false contours. In this work a fuzzy approach of BTC to avoid truncating homogeneous blocks and to preserve smooth edges in two-cluster blocks is proposed. Each image block, viewed as a fuzzy set, is segmented into two clusters using a fuzzy clustering algorithm. The block is then encoded by modified fuzzy weighted means of the two clusters. Initialization strategies of the fuzzy clustering algorithm and a contextual quantization method are proposed. Experimental results show an improvement of visual quality of reconstructed images and peak signal-to-noise ratio when compared to BTC, economical BTC (EBTC), absolute moment BTC (AMBTC), and a minimum mean square error quantizer (MMSEQ). Computation time required by AMBTC, EBTC, and fuzzy BTC methods are reported. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

关键词： image processing image coding block truncation coding fuzzy clustering fuzzy C-means algorithm contextual quantization

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Digital image watermarking technique based on block truncation coding with vector quantization

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CHINESE JOURNAL OF ELECTRONICS 2002年第2期11卷 152-157页

作者： Lu, ZM Liu, CH Sun, SG Harbin Inst Technol Dept Automat Test & Control Harbin 150001 Peoples R China

Digital watermarking has been presented as a new method for copyright protection. This technique embeds a secret signal in a digital image or video sequence that allows one to establish ownership or identify a buyer. The common digital image watermarking techniques are spatial or transform-based, which are based on spread-spectrum communications. Most of transform-domain watermarking methods are based on discrete cosine transforms (DCT) and robust to JPEG lossy compression. Recently, digital image watermarking based on another important lossy compression technique, vector quantization (VQ), has been presented, which carries watermark information by codeword indices. It is secret and efficient, and is robust to VQ compression with the same codebook. block truncation coding (BTC) is a fast lossy image coding technique suitable for real-time image transmission. Both VQ and BTC have some shortcomings that affect their applications to image compression. To reduce edge degradation produced by VQ and BTC, VQ-BTC has been presented as an efficient technique for low-bit-rate image encoding. This paper presents a more efficient image watermarking method based on VQ-BTC. Experimental results show that the proposed technique is efficient and secret.

关键词： digital watermarking copyright protection block truncation coding vector quantization image coding

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Error Prevention and Concealment for Chinese Calligraphy Based on block truncation coding

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International Journal of Computer Processing of Languages 2002年第1期15卷 101-113页

作者： KUO-LUNG HUNG CHIN-CHEN CHANG Department of Computer Science and Information Engineering National Chung Cheng University Chaiyi Taiwan 621 R.O.C.

A considerable amount of calligraphy has been accumulated from past Chinese dynasties. With the arrival of the digital era, this calligraphy is being digitalized. However, when digital representations of the calligraphy are transmitted over a noisy channel, transmission errors usually occur. In this paper, we propose a new error prevention and concealment method for Chinese calligraphy. The basic idea of the method is to extract the image feature from a Chinese calligraphy and use it as the auxiliary information. Next, the auxiliary information is embedded into the BTC-compressed codes of the original image. Therefore, the auxiliary information can be extracted to help with the reconstruction of the errant blocks during the error concealment phase. From our experimental results, the proposed scheme can effectively conceal the errant blocks. Moreover, when comparing our method with related research, the image quality of our proposed method is superior to those of PIR and GSBEC. The superiority is more outstanding when the errant blocks are larger. Therefore, our proposed method is a highly effective error concealment technique for Chinese calligraphy.

关键词： Chinese Calligraphy block truncation coding Side Match Error Concealment

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Optimisation of multi-level block truncation coding

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2001年第5期16卷 445-459页

作者： Chan, KW Chan, KL City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China

block truncation coding (BTC) is very attractive for real-time image coding at moderate bit-rate due to its low computation and storage demands. One major artefact of this image compression technique is edge raggedness. Modifications are mainly in two areas: bit-rate reduction and improvement of the quality of reconstructed image. Our investigation is in the latter area. In our integrated multi-level ETC scheme, the visual quality is substantially improved, the bit-rate is maintained the same as standard ETC and the computational demand is still kept low. We exploit various algorithms and derive new techniques to optimise the performance of multi-level ETC. Dynamic range tuning (DRT) is used to tackle 2-level ETC. Middle group settlement is used to carry out binary classification for tri-modal distribution. For 4-level ETC, an iterative DRT is derived. Based on our experience on 2- and 4-level BTCs, an optimised 3-level BTC is derived. Extensive testing has been carried out on 30 images. The resultant visual quality is nearly perfect and the PSNR may be boasted by up to 7 dB. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： image compression block truncation coding multi-level quantization

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Quadtree-segmented image compression method using vector quantization and cubic B-spline interpolation

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IMAGING SCIENCE JOURNAL 2004年第2期52卷 106-116页

作者： Chang, CC Chuang, JC Chung, CY Natl Chung Cheng Univ Dept Comp Sci & Informat Engn Chiayi 621 Taiwan Natl Chiao Tung Univ Dept Comp & Informat Sci Hsinchu Taiwan

A novel hybrid image compression method based on quadtree is proposed, involving two techniques: vector quantization (VQ) and cubic B-spline interpolation. Traditional block-based image compression methods, such as VQ, block truncation coding and others, do not take the relationship of neighbouring blocks into consideration, which results in a limit to their compression rate. To put it another way, if the relationships between neighbouring blocks can be included in the scheme by application of the quadtree technique and the VQ method, as well as cubic B-spline interpolation, which is exactly what is attempted in this paper, the performance of image compression can be improved significantly. According to the experimental results, this method can achieve satisfactory results in terms of the compression rate, while maintaining an acceptable image quality compared with block-based image compression methods.

关键词： vector quantization cubic B-spline interpolation quadtree bilinear JPEG block truncation coding

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Multilevel block truncation coding of two steps searching

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2001年第8期E84A卷 1977-1980页

作者： Chen, WJ Chung Chou Inst Technol Dept Elect Engn YuanLin 510 Taiwan

In this letter. a new scheme of designing multilevel BTC coding is proposed. The optimal quantization can obtain by selecting the quantization threshold with an exhaustive search. However, it requires an enormous amount of computation and is thus impractical while we take an exhaustive search for the multilevel BTC. A two-steps searching method is applied to reduce the computational complexity. Comparisons of results with various methods have verified that the proposed method approach to the optimal quantization with little computation complexity.

关键词： image coding block truncation coding absolute moment block truncation coding multilevel BTC two-steps search

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Quadtree-segmented image compression method using vector quantization and cubic B-spline interpolation

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The Journal of Photographic Science 2004年第2期52卷 106-116页

关键词： VECTOR QUANTIZATION CUBIC B-SPLINE INTERPOLATION QUADTREE BILINEAR JPEG block truncation coding

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Fundamental error analysis and geometric interpretation for block truncation coding techniques

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SIGNAL PROCESSING-IMAGE COMMUNICATION 2000年第10期15卷 859-867页

作者： Ma, KK Zhu, S Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Comp Mot Inc Goleta CA 93105 USA

Various variants and hybrid approaches evolved from the origin of Delp and Mitchell's block truncation coding (BTC) or moment preserving quantizer (MPQ) have formed a niche as an effective and simple image compression methodology with attractive coding performance achieved at moderate bitrates. As ETC is still lacking a fundamental error analysis, in this paper we present some fundamental insights regarding one-bit (or two-level) BTC's truncation error by providing mathematical analysis as well as novel geometric interpretation. We further show that the mean-square error (MSE) of Lema and Mitchell's absolute moment block truncation coding (AMBTC) is always bounded below (i.e., less than or equal to) that of ETC. Therefore, with additional advantages in computation and implementation, AMBTC is always superior. Furthermore, we developed a new adaptive equal sign position optimization (ESPO) algorithm for optimum pixel classification. Our quantization error analysis shows that incorporating the ESPO algorithm into conventional AMBTC or ETC achieves minimum MSE in either case. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： image coding block truncation coding moment preserving quantizer absolute moment block truncation coding equal sign position optimization

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