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block truncation coding USING HOPFIELD NEURAL NETWORK

ELECTRONICS LETTERS 1992年第23期28卷 2144-2145页

作者： MITCHELL, HB DORFAN, M Elta Electronics Industries Ltd. Ashdod Israel

The authors extend the analysis of the block truncation coding (BTC) algorithm using a Hopfield neural network (HNN). They show that its performance is suboptimum (in the mean square error sense) and that alternative ... 详细信息

关键词： block truncation coding IMAGE coding NEURAL NETWORKS

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block truncation coding WITH ENTROPY coding

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IEEE TRANSACTIONS ON COMMUNICATIONS 1995年第2-4期43卷 1677-1685页

作者： FRANTI, P NEVALAINEN, O Department of Computer Science University of Turku Turku Finland

block truncation coding (ETC) is a simple and fast image compression algorithm which achieves constant bit rate of 2.0 bits per pixel, The method is however suboptimal. In the present paper we propose a modification of ETC in which the compression ratio will be improved by coding the quantization data and the bit plane by arithmetic coding with an adaptive modelling scheme. The results compare favorable with other ETC variants. The bit rate for test image Lena is 1.53 bits per pixel with the mean square error of 16.51.

关键词： compression ratio constant bit rate (CBR) pixel image compression algorithm Entropy coding arithmetic coding Mean square error block truncation coding

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block truncation coding based effective watermarking scheme for image authentication with recovery capability

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MULTIMEDIA TOOLS AND APPLICATIONS 2019年第4期78卷 4197-4215页

作者： Singh, Durgesh Singh, Sanjay K. Indian Inst Technol BHU Dept Comp Sci & Engn Varanasi 221005 Uttar Pradesh India

Due to the advancement of photo-editing software, powerful computers and high resolution capturing devices, it has become tough to prevent the digital image from tampering. So, in these days just by looking a digital image we cannot say whether it is a genuine or not. This is why digital image authentication, as well as restoration, has become the essential issues, especially when it is utilized in medical science, evidence of court, and forensic science. This paper proposes an effective self-embedding fragile watermarking technique for the digital image authentication as well as recovery. The watermark is generated by quantization, and block truncation coding (BTC) of each 2 x 2 non-overlapping block and embedded in three least significant bits (LSBs) of the corresponding mapped block. The recovery bits are derived from most significant bits (MSBs) of the host image, and the authentication bits are derived from recovery bits, the spatial location of pixels and watermark keys. Even if tempering rate is 50%, the reconstruction of tampered image is achieved with high peak signal-to-noise ratio (PSNR) and normalized correlation coefficient (NCC). The experimental results demonstrate that the proposed scheme not only outperforms high-quality recovery fidelity but also negotiate the blocking artifacts additionally it improves the accuracy of tamper localization due to the use of very small size blocks.

关键词： Digital image watermarking Self-embedding watermarking block truncation coding Image authentication Image restoration

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block truncation coding using pattern fitting

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PATTERN RECOGNITION 2004年第11期37卷 2131-2139页

作者： Dhara, BC Chanda, B Indian Stat Inst Elect & Commun Sci Kolkata 700108 India Jadavpur Univ Dept Informat Technol Kolkata 700098 India

block truncation coding (BTC) divides an image into blocks having given size and then encodes each block by two representative gray levels and a bit-pattern. In this work a modified scheme of BTC is proposed where the computed representative gray levels are the bias and the contrast in each block. Secondly, instead of determining bit-pattern for each block, an optimum bit-pattern is selected from a pattern-book. Thus the index of the optimum pattern is used to encode in lieu of the explicit pattern. Thirdly, if the contrast is low the block is assumed to be smooth and bit-pattern is not required to reconstruct the block. This leads to significant reduction in bit-rate (bpp). Finally, the contrast component and the predictive residual of the bias component are entropy coded to achieve further reduction in bpp. Performance of the proposed scheme is measured in terms of peak-signal-to-noise ratio and bpp, and is compared with other recently reported methods. (C) 2004 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.

关键词： image coding block truncation coding vector quantization pattern fitting

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block truncation coding for color images using vector quantization

Block truncation coding for color images using vector quanti...

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Hybrid Image and Signal Processing V Conference

作者： Celenk, M Wu, JS OHIO UNIV STOCKER CTRSCH ELECT ENGN & COMP SCIATHENSOH 45701

ISBN: (纸本)0819421324

The method of block truncation coding (BTC) was originally proposed by Delp and Mitchell and later extended to color images by others. The idea is to retain important visual features while discarding details which are not to be noticeable to human observers. In our paper, we further explore the block truncation coding method by minimizing the within group variance measure proposed by Otsu and the information distance suggested by Kullback to divide every 4 by 4 subimage into two classes, and an intuitive vector quantizer to further compress the coded output. As a result of the combined application of BTC and vector quantization methods, we get better bit rates (bits per pixel) for the test image used in experiments without significant perceivable errors in its appearance. First, we divide a color image into 4 by 4 small nonoverlapping blocks. The Otsu or Kullback thresholding technique is then used as an optimal method to minimize the mean square error of classifying each pixel in a block into two classes and encode it in one-bit adaptive vector quantizer. After classification, for each 4 by 4 block, there is a bitmap corresponding to one-bit adaptive vector quantizer and a six-dimensional mean vector corresponding to each of the two classes. In the second part, the vector quantizer proposed by Linde, Buzo and Gary (known as LBG) is used to compress the bit-map and mean vectors separately. This is a six- dimensional signal compression for the mean vectors and a binary compression for the bitmap. Vector quantization of these BTC output results in a reduction of the bit rate of the coder. By using BTC and vector quantization methods, we have obtained 1.0 bit/pixel compression result for a color image of size 512 by 480 given with 8 bits/pixel and R, G, B specifications. The mean square error was also measured as low as 0.07 without much deformation in the reconstructed image.

关键词： block truncation coding color image vector quantization

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block truncation coding-based Audio Compression Technique 2018

Block Truncation Coding-based Audio Compression Technique

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2nd International Conference on Digital Signal Processing (ICDSP) / International Conference on Computer Graphics and Virtuality (ICCGV)

作者： Dacles, Mark Daniel I. Daga, Ryan Rey M. Univ Philippines Visayas Tacloban Coll Tacloban City Leyte Philippines

ISBN: (纸本)9781450364027

There have been an increasing utilization and consumption of audio files in various applications across different desktop and mobile devices. Thus, audio data compression has been beneficial in reducing the bandwidth and disk space requirements of such data. block truncation coding (BTC), a well-known data compression technique for digital images, was used as the underlying algorithm in encoding audio data. A new encoding technique for audio data was proposed with the following components: (1) quadtree for audio block segmentation, (2) AMBTC for computation of representative values, and (3) Huffman coding for lossless data representation. The performance of the proposed encoding technique was benchmarked and measured using Peak Signal-to-Noise Ratio (PSNR) and compression rate.

关键词： Audio data compression block truncation coding quadtree Huffman coding

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block truncation coding using a set of predefined bit planes

Block truncation coding using a set of predefined bit planes

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7th International Conference on Computational Intelligence and Multimedia Applications

作者： Amarunnishad, T. M. Govindan, V. K. Mathew, Abraham T. NIT Dept Elect Engn Calicut Kerala India

ISBN: (纸本)0769530508

A simple and easy to implement method to improve the block truncation coding (BTC) is proposed for image compression. A set of predefined bit planes is defined independently of the images to be encoded. The bit rate is considerably reduced by encoding the index of the predefined bit planes using Huffman encoding. Experimental results show that at lower bit rate the proposed method provides acceptable visual quality reconstructed images.

关键词： image compression block truncation coding bit rate peak signal to noise ratio

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User-friendly secret image sharing scheme with verification ability based on block truncation coding and error diffusion

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2015年 29卷 46-60页

作者： Qu, Duanhao Ye, Lili Sun, Wei Sun Yat Sen Univ Sch Informat Sci & Technol Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Sch Software Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Sch Informat Management Guangzhou 510006 Guangdong Peoples R China Chinese Acad Sci Inst Informat Engn State Key Lab Informat Secur Beijing 100093 Peoples R China

Conventional secret image sharing schemes, which are constructed based on Shamir's method, often suffer from random-liked shares, lossy reconstruction and high computation complexity. In addition, their generated shares are generally in original image format which may lead to more storage and suspicion from invaders. In this paper, we propose a user-friendly secret image sharing scheme based on block truncation coding (BTC) and error diffusion, where meaningful shares can be directly generated without any extra process. The meaningful shares by the proposed scheme are in BTC-compressed format which can reduce the capacity of transfer and storage. In the reconstructing phase, the secret image can be loss-lessly reconstructed by performing XOR operations on bit planes of sufficient BTC-compressed shares. Further, the proposed scheme provides extra verification ability to identify cheaters and check false shares. Theoretical analysis and simulation results demonstrate the feasibility of the proposed scheme. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Secret image sharing block truncation coding Error diffusion Meaningful shares Loss less reconstruction Verification ability Low computation complexity XOR operation

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A COMPARISON OF DIFFERENT block truncation coding ALGORITHMS FOR IMAGE COMPRESSION

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SIGNAL PROCESSING-IMAGE COMMUNICATION 1994年第1期6卷 77-82页

作者： MITCHELL, HB ZILVERBERG, N AVRAHAM, M Signal Processing and Computing Division Elta Electronics Industries Ltd Ashdod Israel

Many different versions of the block truncation coding image compression algorithm exist. In this paper we compare the different versions from the viewpoint of reconstructed image quality and computational complexity.

关键词： block truncation coding IMAGE coding

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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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