With the development of the Internet, new requirements are put forward on image compression effect, compression ratio and encoding and decoding time. The principle of fractalcoding is novel. It breaks through the tra...
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ISBN:
(纸本)9781467329644;9781467329637
With the development of the Internet, new requirements are put forward on image compression effect, compression ratio and encoding and decoding time. The principle of fractalcoding is novel. It breaks through the traditional entropy boundary theory. Especially its high compression ratio makes the fractal image coding become a hot research point. But this method has the encoding and decoding lopsided problem. Based on the basic principle of fractalimage compression, this paper proposes a calculation method which is based on the main diagonal, namely only using the two diagonal data to do mean calculation. Thus not only reduce the data in operation, but also make the time be reduced to a certain degree. The experimental results show that, under the same quality of the image reconstruction, the algorithm makes the encoding and decoding time be greatly reduced
作者：
Furao, ShenHasegawa, OsamuTIT
Dept Computat Intelligence & Syst Sci Midori Ku R2-52 Imaging Sci & Engn Lab4259 Nagatsuta Yokohama Kanagawa 2268503 Japan Tokyo Inst Technol
Imaging Sci & Engn Lab Midori Ku Yokohama Kanagawa 2268503 Japan
The main shortcomings of fractalimage coders are (1) the slow speed for searching domain block pool, and (2) known fast algorithms leading to a loss of image quality. We propose efficient fractal image coding using s...
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The main shortcomings of fractalimage coders are (1) the slow speed for searching domain block pool, and (2) known fast algorithms leading to a loss of image quality. We propose efficient fractal image coding using simulated annealing method. Compared to previous schemes, our proposal greatly increases the search speed of domain block pool with almost no image quality loss. Experimental results indicate the high feasibility of the proposed method, which is, furthermore, extendable to other fractal coders.
fractal image coding, the traditional approaches which are being used currently, based on dividing the images into blocks. These blocks are known as range blocks and domain blocks. In these of approaches after coding ...
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ISBN:
(纸本)9783642257339
fractal image coding, the traditional approaches which are being used currently, based on dividing the images into blocks. These blocks are known as range blocks and domain blocks. In these of approaches after coding the image generally the decoding process is slow as extensive searching is required. In this paper we are going to present a scheme which uses the concept of self similarity at small scale that is at pixel level. Through this proposed scheme coding and decoding can be speed-up.
This paper presents an improved fractal block coding scheme for still images. The proposed scheme employs a new technique which we call "sub-block luminance level shifting." In fractal block coding, an input...
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ISBN:
(纸本)0819437034
This paper presents an improved fractal block coding scheme for still images. The proposed scheme employs a new technique which we call "sub-block luminance level shifting." In fractal block coding, an input image is first partitioned into range blocks. Each range block is encoded by a set of contractive affine transformations of its corresponding domain block. One of the coded data for each range block is an average pixel value of the range block, which is used for luminance level shifting between the range block and the contracted domain block. in our proposed method, a range block is further partitioned into sub-blocks in some cases and an average value of each sub-block instead of the range block is used for luminance level shifting. We have proposed an improved fractal block coding scheme applying this sub-block luminance level shifting adaptively block-by-block basis and also combining this method with adaptive range block size fractalcoding. The computer simulation results show that the proposed fractalcoding scheme gives higher SNR (Signal-to-Noise Ratio) values and better image qualities compared to the conventional fractal block coding scheme.
A novel paradigm for fractalcoding selectively corrects the fractal code for selected domain blocks with an image-adaptive VQ codebook. The codebook is generated from the initial uncorrected fractal code and is, ther...
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A novel paradigm for fractalcoding selectively corrects the fractal code for selected domain blocks with an image-adaptive VQ codebook. The codebook is generated from the initial uncorrected fractal code and is, therefore, available at the decoder. An efficient trade-off is generated between incremental performance and bit rate.
In this paper some modifications of fractal image coding are presented. Proposed methods are based on correlation coefficients computing as an alternative approach to searching of similarity between blocks. The conver...
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In this paper some modifications of fractal image coding are presented. Proposed methods are based on correlation coefficients computing as an alternative approach to searching of similarity between blocks. The convergence speed of decoding process is faster then convergence speed of standard method. The convergence process with modified start conditions of decoding process are analysed and verified on gray scale static images too.
In this paper is presented a new approach in fractal image coding based on trigonometric approximation. The least square approximation method is used for approximation of blocks in standard fractalimage compression a...
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In this paper is presented a new approach in fractal image coding based on trigonometric approximation. The least square approximation method is used for approximation of blocks in standard fractalimage compression algorithm. In the paper is shown that it is possible to use also trigonometric approximation for describing of blocks in fractal image coding. This approximation was implemented and analyzed from point of view of quality of reconstructed images. The experimental results of this method were tested on static grayscale images.
In this paper, we propose a fast fractal image coding based on LMSE (least mean square error) analysis and subblock feature. The proposed method focuses on efficient search of contrast scaling, position of its matched...
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In this paper, we propose a fast fractal image coding based on LMSE (least mean square error) analysis and subblock feature. The proposed method focuses on efficient search of contrast scaling, position of its matched domain block, and isometric transform for a range block. The contrast scaling and the domain block position are searched using a cost function that comes from the LMSE analysis of the range block and its fractal-approximated block. The isometric transform is searched using 2 x 2 blocks formed with the averages of subblocks of range block and domain block. Experimental results show that the encoding time of a conventional fractal image coding with our search method is 25.6-39.7 times faster than that with full search method at the same bit rate while giving PSNR decrement of 0.2-0.7 dB with negligible deterioration in subjective quality. It is also shown that the encoding time of a conventional fractal image coding with our search method is 3.4-4.2 times faster than Jacquin's fractal image coding and is superior by maximum 0.8 dB in PSNR. It also yields reconstructed images of better quality.
In recent work, various fractal image coding methods are reported, which adopt the self-similarity of images to compress the size of images. However, till now, no solutions for the security of fractal encoded images h...
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In recent work, various fractal image coding methods are reported, which adopt the self-similarity of images to compress the size of images. However, till now, no solutions for the security of fractal encoded images have been provided. In this paper, a secure fractal image coding scheme is proposed and evaluated, which encrypts some of the fractal parameters during fractal encoding, and thus, produces the encrypted and encoded image. The encrypted image can only be recovered by the correct key. To maintain security and efficiency, only the suitable parameters are selected and encrypted through investigating the properties of various fractal parameters, including parameter space, parameter distribution and parameter sensitivity. The encryption process does not change the file format, keeps secure in perception, and costs little time or computational resources. These properties make it suitable for secure image encoding or transmission.
Iteration in conventional fractalcoding schemes nut only leads to a high computation complexity, but also requires a large amount of memory. It unavoidly prolongs the decoding process and precludes the use of high sp...
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Iteration in conventional fractalcoding schemes nut only leads to a high computation complexity, but also requires a large amount of memory. It unavoidly prolongs the decoding process and precludes the use of high speed applications. To overcome these problems, we propose a non-iterative method based on a novel domain pool design for fractal image coding. The domain pool used in the encoder is on-line transmitted to the decoder. Therefore, the domain blocks are generated from the same mean image existing in both the encoder and decoder. We next ultilize contractive affine transformations to encode/decode the image with iterations. From the simulation results, we have successfully speeded up the decoding process, and the coding performance for the test images is good as or even better than that of the conventional schemes.
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