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Modified decoded image quality prediction method for fractal image coding

COMPUTERS & ELECTRICAL ENGINEERING 2024年第PartB期118卷

作者： Wang, Qiang Du, Jingjing Dalian Maritime Univ Coll Informat Sci & Technol Linghai Rd 1 Dalian 116026 Peoples R China Hengshui Univ Coll Elect & Informat Engn Hengshui 053000 Peoples R China

An effective method was proposed to improve the performance of fractal decoded image quality prediction. Firstly, we found that the dynamic range of the linear correlation coefficients (LCCs) between range blocks and their respective best-matched domain blocks was significantly extended by a small number of outliers which contribute little to accumulated collage error and reduced the prediction accuracy. Secondly, to remove the outliers of LCCs, we introduced the effective minimum and maximum of LCCs that can provide the effective bottom and top limits of the actual percentage of accumulated collage error (APACE), EBL-APACE and ETL-APACE, respectively. Finally, by estimating APACE with the average of EBL-APACE and ETL-APACE, the decoded image quality can be directly predicted with the accumulated collage error divided by the estimated APACE. Three state-of-the-art and conventional fractal encoding methods were adopted to verify the effectiveness of the proposed method. Experimental results show that the proposed method can reduce the computational complexity by 2%-7% while maintaining comparable or higher prediction accuracy regarding the previous method.

关键词： fractal image coding Decoded image quality Accumulated collage error Average collage error

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Hybrid fractal image coding

Hybrid Fractal Image Coding

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7th International Conference on Communications, Signal Processing, and Systems (CSPS)

作者： Jin, Guohua Wang, Qiang Bi, Sheng Dalian Maritime Univ Coll Informat Sci & Technol Dalian Peoples R China

ISBN: (纸本)9789811365041;9789811365034

In order to improve the performance of fractal coding methods, a new method is proposed in this paper. Firstly, we find that the range blocks with large variances play a more important role in causing the degradation of decoded images, and the effect of the remaining range blocks can be ignored. Secondly, the range blocks with larger variances will be encoded in an extended domain block pool, and the remaining ones will be encoded with the no-search fractal encoding method. Finally, two fractal coding methods are used to assess the performance of the proposed method. Experiments show that compared with the previous methods, the proposed method can provide shorter encoding time, better quality of decoded images and fewer bits per pixel.

关键词： fractal image coding Collage error No-search Quality of decoded images

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A PRIMAL-DUAL ALGORITHM FOR ROBUST fractal image coding

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fractalS-COMPLEX GEOMETRY PATTERNS AND SCALING IN NATURE AND SOCIETY 2019年第7期27卷

作者： Xu, Chen Ye, Yuting Hu, Zhenwei Zou, Yuru Shen, Lixin Liu, Xiaoxia Liu, Jian Shenzhen Univ Coll Math & Stat Shenzhen Key Lab Adv Machine Learning & Applicat Shenzhen 518060 Guangdong Peoples R China Syracuse Univ Dept Math Syracuse NY 13244 USA Shenzhen Univ Guangdong Key Lab Intelligent Informat Proc Shenzhen 518060 Guangdong Peoples R China

The essence of Huber fractal image coding (HFIC) is to predict the fractal code of a noiseless image as accurately as possible from its corrupted observation with outliers by adopting Huber M-estimation technique. However, the traditional HFIC is not quite satisfactory mainly due to the absence of contractivity restriction for the estimate of the fractal parameters (actually, it is a fundamental requirement in the theory of fractal image coding). In this paper, we introduce a primal-dual algorithm for robust fractal image coding (PD-RFIC), which formulates the problem of robust prediction of the fractal parameters with contractivity condition as a constrained optimization model and then adopts a primal-dual algorithm to solve it. Furthermore, in order to relieve using the corrupted domain block as the independent variable in the proposed method, instead of using the mean operation on a 2 x 2 subblock in the traditional HFIC, we apply a median operation on a larger subblock to obtain the contracted domain blocks for achieving the robustness against outliers. The effectiveness of the proposed method is experimentally illustrated on problems of image denoising with impulse noise (specifically, salt & pepper noise and random-valued noise). Remarkable improvements of the proposed method over conventional HFIC are demonstrated in terms of both numerical evaluations and visual quality. In addition, a median-based version of Fisher classification method is also developed to accelerate the encoding speed of the proposed method.

关键词： fractal image coding Primal-Dual Algorithm Median-Based Fisher's Classification Impulse Noise

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Perceptual image hashing based on structural fractal features of image coding and ring partition

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MULTIMEDIA TOOLS AND APPLICATIONS 2020年第27-28期79卷 19025-19044页

作者： Khelaifi, Fares He, HongJie Southwest Jioatong Univ Sch Informat Sci & Technol Chengdu 610031 Peoples R China

Perceptual image hashing finds increasing attention in several multimedia security applications. However, reaching the trade-off balance between the two most important properties of image hashing- robustness and discrimination, still remains the most restive challenge in hashing schemes. In this study, a robust image hashing technique is proposed by incorporating ring partition and fractal image coding. The scheme starts by normalizing the image to help in extracting its local features. Then the concept of ring partition is introduced in order to make our hash rotation invariant by dividing the image into 5 different rings to form a secondary image that possesses the invariant property. Further, image coding is introduced by extracting the structural fractal features to exploit dimensionality reduction and compression, hence, generating a robust hash. To ensure the system's security, encryption is performed on the generated fractal elements before the final hash construction. We conduct series of experiments to evaluate the performance of our scheme. The achieved result shows that our scheme is robust against several content-preserving attacks such as image rotation, JPEG compression, gamma correction, gaussian low pass filtering, image scaling, cropping, brightness adjustment and contrast adjustment. In addition, the receiver operating characteristics is used to show the discriminative capability and robustness of our scheme as compared to other state-of-art schemes in the literature.

关键词： Perceptual image hashing Ring partition Feature extraction fractal image coding Hash generation

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An adaptive fractal-based image coding with hierarchical classification strategy and its modifications

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INNOVATIONS IN SYSTEMS AND SOFTWARE ENGINEERING 2019年第1期15卷 35-42页

作者： Nandi, Utpal Vidyasagar Univ Dept Comp Sci Midnapore 721102 W Bengal India

fractal-based image coding is one of the efficient methods for grayscale image since the reconstructed images are resolution independent and also has low reconstruction time. This paper discusses the efficiency of hierarchical classification strategy for fractal image coding that uses adaptive quadtree partitioning. The scheme forms two level hierarchical domain groups and ranges are matched with similar hierarchical domain class. The fractal image coding technique with hierarchical classification strategy is then modified also to improve the compression ratio by using an efficient loss-less coding scheme OLZW on fractal compressed image. A variant of OLZW, i.e., MOLZW is also applied for the same. These modified variants show their significant improvements in compression ratio without degradation of image quality.

关键词： fractal image coding Hierarchical classification PSNR Loss-less coding Adaptive quadtree partitioning

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Improved method for predicting the peak signal-to-noise ratio quality of decoded images in fractal image coding

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JOURNAL OF ELECTRONIC IMAGING 2017年第1期26卷 013024-013024页

作者： Wang, Qiang Bi, Sheng Dalian Maritime Univ Coll Informat Sci & Technol Dalian Peoples R China

To predict the peak signal-to-noise ratio (PSNR) quality of decoded images in fractal image coding more efficiently and accurately, an improved method is proposed. After some derivations and analyses, we find that the linear correlation coefficients between coded range blocks and their respective best-matched domain blocks can determine the dynamic range of their collage errors, which can also provide the minimum and the maximum of the accumulated collage error (ACE) of uncoded range blocks. Moreover, the dynamic range of the actual percentage of accumulated collage error (APACE), APACEmin to APACEmax, can be determined as well. When APACEmin reaches a large value, such as 90%, APACEmin to APACEmax will be limited in a small range and APACE can be computed approximately. Furthermore, with ACE and the approximate APACE, the ACE of all range blocks and the average collage error (ACER) can be obtained. Finally, with the logarithmic relationship between ACER and the PSNR quality of decoded images, the PSNR quality of decoded images can be predicted directly. Experiments show that compared with the previous similar method, the proposed method can predict the PSNR quality of decoded images more accurately and needs less computation time simultaneously. (C) 2017 SPIE and IS&T

关键词： fractal image coding average collage error peak signal-to-noise ratio quality of decoded images

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A Novel Method to Improve the Quality of Decoded images in fractal image coding 8

A Novel Method to Improve the Quality of Decoded Images in F...

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Proceedings 2015 8 International Congress on image and Signal Processing (CISP)

作者： Zou, Kun Wang, Qiang Zhai, Zhaoxia Dalian Maritime Univ Coll Informat Sci & Technol Dalian 116026 Peoples R China

ISBN: (纸本)9781467390989

In order to improve the quality of decoded images in fractal image coding, a novel method by making use of a modified image is proposed in this paper. Since the degradation of decoded images in fractal coding mainly comes from the poor self-similarity of the input image, a modified image that satisfies good self-similarity and approximates the original image well is constructed. After transforming the input image into the modified image and performing fractal coding method on it, the decoded image with higher quality can be obtained. Simulations show that compared with the conventional fractal coding method, while the same compression ratio is maintained, the proposed method can provide higher PSNR at the expense of slightly longer encoding time.

关键词： fractal image coding Collage error Quality of decoded images

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An Accelerated Method to Predict the Quality of Decoded images in fractal image coding 8

An Accelerated Method to Predict the Quality of Decoded Imag...

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Proceedings 2015 8 International Congress on image and Signal Processing (CISP)

作者： Wang, Qiang Bi, Sheng Jin, Guohua Dalian Maritime Univ Coll Informat Sci & Technol Dalian 116026 Peoples R China

ISBN: (纸本)9781467390989

With many observations, we find that there exists a logarithmic relationship between the average collage error (ACER) and the quality of decoded images. By making use of the ACER in the encoding process, the quality of decoded images can be predicted without fractal decoding. In order to shorten the prediction process further, an accelerated version of the prediction method is proposed. By theoretical derivations and analyses, a low limit of accumulated collage error (LLPACE) is introduced which provides an effective way to evaluate the percentage of total collage error accounted by the accumulated collage error (ACE). Experiments show that for either basic fractal coding or other three fast fractal coding methods, the accelerated prediction method can provide satisfying performance and reduce about one third of total computations in the encoding process.

关键词： fractal image coding Quality of decoded images Accumulated collage error Average collage error

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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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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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