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State-space approach to roundoff error analysis of fractal image coding

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 1997年第1期E80A卷 159-165页

作者： Lee, CH Kawamata, M Higuchi, T Graduate School of Information Sciences Tohoku University Sendai-shi 980-77 Japan Graduate School of Engineering Tohoku University Sendai-shi 980-77 Japan

Roundoff error due to iterative computation with finite wordlength degrades the quality of decoded images in fractal image coding that employs a deterministic iterated function system. This paper presents a state-space approach to round-off error analysis of fractal image coding for grey-scale images. The output noise variance matrix and the noise matrix are derived for the measures of error and the output noise variance is newly defined as the pixel mean of diagonal elements of the output noise matrix. A quantitative comparison of experimental roundoff error with analytical result is made for the output noise variance. The result shows that our analysis method is valid for the fractal image coding. Our analysis method is useful to design a real-time and low-cost decoding hardware with finite wordlength for fractal image coding.

关键词： fractal image coding iterated function systems roundoff error analysis state-space approach

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Discrete wavelet transform-based simple range classification strategies for fractal image coding

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NONLINEAR DYNAMICS 2014年第3期75卷 439-448页

作者： Wang, Xing-Yuan Zhang, Dou-Dou Dalian Univ Technol Fac Elect Informat & Elect Engn Dalian 116024 Peoples R China

An efficient fractal method based on discrete wavelet transfer is proposed in this paper. Before encoding, images with one-level wavelet transform are first partitioned into four subbands, which classify the range blocks as four types. An accelerated fractal coding method called variance sorting (VS) scheme with high reconstructed quality is addressed for the low-frequency components. Hereafter, the low-frequency part rebuilt performs one-level wavelet decomposition once again. The first-level high-frequency subbands excluding the diagonal directions are predicted according to the next coarser frequency scale in the same directions. Simulation experimental results compared with other classification algorithms demonstrate that the proposed method can obtain high compression ratio and reduce the encoding time without significant loss in the reconstructed image quality.

关键词： fractal image coding Discrete wavelet transform Range classification Variance sorting High compression ratio

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A fast fractal image coding based on kick-out and zero contrast conditions

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IEEE TRANSACTIONS ON image PROCESSING 2003年第11期12卷 1398-1403页

作者： Lai, CM Lam, KM Siu, WC Hong Kong Polytech Univ Dept Elect & Informat Engn Ctr Multimedia Signal Proc Hong Kong Hong Kong Peoples R China

A fast algorithm for fractal image coding based on a single kick-out condition and the zero contrast prediction is proposed in this paper. The single kick-out condition can avoid a large number of range-domain block matches when finding the best matched domain block. An efficient method for zero contrast prediction is also proposed, which can determine whether the contrast factor for a domain block is zero or not, and compute the corresponding difference between the range block and the transformed domain block efficiently and exactly. The proposed algorithm can achieve the same reconstructed image quality as the exhaustive search, and can greatly reduce the required computation or runtime. In addition, this algorithm does not need any pre-processing step or additional memory for its implementation, and can combine with other fast fractal algorithms to further improve the speed. Experimental results show that the runtime is reduced by about 50% of that of the exhaustive search method. When combined with the DCT Inner Product algorithm, the required runtime for the algorithm can be further reduced by about 50%. The proposed algorithm was also compared to two other fast fractal algorithms. Experimental results also show that our algorithm achieves a better efficiency and requires a much smaller amount of memory for implementation.

关键词： fractal image coding full search image compression zero contrast

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CRYPTANALYSIS ON SECURE fractal image coding BASED ON fractal PARAMETER ENCRYPTION

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fractalS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY 2012年第1期20卷 41-51页

作者： Yuen, Ching-Hung Wong, Kwok-Wo City Univ Hong Kong Dept Elect Engn Kowloon Tong Hong Kong Peoples R China

The vulnerabilities of the selective encryption scheme for fractal image coding proposed by Lian et al.(1) are identified. By comparing multiple cipher-images of the same plain-image encrypted with different keys, the positions of unencrypted parameters in each encoded block are located. This allows the adversary to recover the encrypted depth of the quadtree by observing the length of each matched domain block. With this depth information and the unencrypted parameters, the adversary is able to reconstruct an intelligent image. Experimental results show that some standard test images can be successfully decoded and recognized by replacing the encrypted contrast scaling factor and brightness offset with specific values. Some remedial approaches are suggested to enhance the security of the scheme.

关键词： fractal image coding Joint image Compression and Encryption Selective Encryption Cryptanalysis

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Adaptive fractal image coding in subband domain

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JOURNAL OF THE CHINESE INSTITUTE OF ENGINEERS 1996年第3期19卷 417-427页

作者： Chen, RJ Chieu, BC NATL TAIWAN INST TECHNOL DEPT ELECTR ENGN TAIPEI 106 TAIWAN NATL LIENHO COLL TECHNOL & COMMERCE DEPT ELECTR ENGN MIAOLI 360 TAIWAN

In this paper, we propose and evaluate a method for fractal image coding in the subband domain. The subband decomposition scheme acts as a classifier, which can efficiently reduce encoding time. The proposed fractal image coding scheme is an adaptive one. The adapt ability is based on the variance of each subband. At each subband, the scheme adaptively sets the map block size that should be encoded. In addition, the domain blocks are adaptively restricted to the neighborhood of their respective range block. Simulation results show that good picture quality of the coded image is obtained at 0.370 bpp. It also indicates that such an adaptive scheme makes a better trade-off between the required bit rate and picture quality than a fixed size one. Moreover, the adaptive scheme can save a large amount of time.

关键词： subband decomposition/reconstruction fractal image coding

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Split decision functions in fractal image coding

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ELECTRONICS LETTERS 1998年第8期34卷 751-753页

作者： Distasi, R Polvere, M Nappi, M Univ Salerno Dipartimento Informat & Applicaz RM Capocelli I-84081 Baronissi SA Italy

Quadtree partitions are often used in fractal image compression to achieve variable bit rates. The authors present an entropy based split decision function that can improve image quality and speed up the encoding process. Furthermore, other widespread split decision functions are discussed, along with the advantages offered by adaptive thresholds.

关键词： fractal image coding Pattern recognition variable bit rates encoding process speedup image quality data compression Codes Combinatorial mathematics quadtree partitions quadtrees entropy based split decision function image coding Optical information, image and video signal processing entropy adaptive thresholds Computer vision and image processing techniques image compression fractals Information theory

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A novel fast fractal image coding algorithm based on texture feature

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IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING 2012年第5期7卷 521-528页

作者： Wang, Wei Ren, Fuji Suzuki, Motoyuki Univ Tokushima Fac Engn Tokushima 7708506 Japan Univ Tokushima Grad Sch Adv Technol & Sci Tokushima 7708506 Japan Hefei Univ Technol AIM Hefei 230009 Arhui Peoples R China

A novel, fast fractal image coding algorithm based on the texture feature is proposed in this paper. fractal image coding is a very promising technique for image compression. However, it has not been widely used because of the long encoding time and high computational complexity. The most fractal image encoding time is spent in determining the approximate D-block from a large D-blocks library by using the global searching method. Clustering the D-blocks library is an effective method to reduce the encoding time. First, all the D-blocks are clustered into several parts based on the new texture feature a derived from variation function;second, for each R-block, the approximate D-blocks are searched for in the same part. In the search process, we import control parameter d;this step avoids losing the most approximate D-block for each R-block. Finally, the R-blocks whose least errors are larger than the threshold given in advance are coded by the quad tree method. We have performed a simulation with MATLABR2010a to verify the effectiveness of the proposed algorithm. The experimental results show that the proposed algorithm can be over 6 times faster than the moment-feature-based fractal image algorithm;in addition, the proposed algorithm also improves the quality of the decoded image and increases the PSNR's average value by 2 dB. The comparisons demonstrate that this method is better than the fractal image coding algorithm based on statistical features. (c) 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

关键词： fractal image coding IFS fractal codes texture feature variation function

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AN IMPROVED fractal image coding METHOD

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fractalS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY 2009年第4期17卷 451-457页

作者： Wang, Xing-Yuan Li, Fan-Ping Chen, Zhi-Feng Dalian Univ Technol Sch Elect & Informat Engn Dalian 116024 Peoples R China

This paper presents a fast fractal image coding method based on quadtree division, improved neighbor search and asymptotic strategy. We search the optimal matched domain block of a range block in its five nearest neighbor blocks and make asymptotic moves along the direction of potential optimal solution. If the optimal solution can not be improved, we carry out quadtree division for this range block until it caters to our demand or reaches greatest division level. The experimental results show that the coding speed of the proposed method declined slightly, but it has a better quality of reconstructed image and higher compression ratio in comparisons with no search method.

关键词： fractal image coding Quadtree Division Asymptotic Strategy Neighbor Search

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Digital watermarking based on fractal image coding using DWT and HVS

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INTERNATIONAL JOURNAL OF KNOWLEDGE-BASED AND INTELLIGENT ENGINEERING SYSTEMS 2014年第2期18卷 81-89页

作者： Ohga, Satoshi Hamabe, Ryuji Fukuoka Jyoto High Sch Fukuoka Japan Fukuoka Inst Technol Dept Comp Sci & Engn Higashi Ku 3-30-1 Wajirohigashi Fukuoka 8110295 Japan

In this paper, we propose a new digital watermarking method based on fractal image coding using DWT and HVS. The method decomposes an original image into subbands LL1 and LL2 using DWT. In fractal image coding, LL1 and LL2 are used for the range blocks region and domain blocks region, respectively. This scheme can embed the watermark robustly against JPEG compression because it embeds the watermark sequence into the subband LL1 using fractal image coding. In addition, the quality of the watermarked image is good in spite of embedding into LL1, because we handle the fractal processing to only the candidate range blocks selected by an embedding judgment processing based on HVS. Experimental results show that the proposed method not only improves robustness against JPEG compression but also improves the quality of the watermarked image when compared with conventional techniques.

关键词： Digital watermarking fractal image coding discrete wavelet transform human visual system

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A Novel fractal image coding based on Basis Block Dictionary

A Novel Fractal Image Coding based on Basis Block Dictionary

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International Conference on E-Learning, E-Business, Enterprise Information Systems and E-Government

作者： Zhao, Ying Hu, Jing Chi, Dongxiang Li, Ming Shanghai Dian Ji Univ Sch Elect & Informat Shanghai Peoples R China

ISBN: (纸本)9780769539072

Long encoding time is the bottleneck in the developing of fractal image coding. Although some improved methods are proposed, the contradiction between encoding time and decoding quality is a still ubiquitous problem. To solve this problem, a novel fractal image coding method based on basis block dictionary is proposed. Multi-component dictionary, which is over-complete, is built under the generative framework by sparse coding. It optimizes the structure of domain pool in fractal coding, and improves the speed of fractal encoding greatly. Finally, the experiments prove the effectiveness and practicality of proposed algorithm.

关键词： fractal image coding iterated function systems basis block dictionary

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