• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2789-2800
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• 1996

Real time fractal coding for successive QCIF 144*176 luminance images has been implemented on a 50MHz IBM 486 personal computer. To satisfy the frame encoding speed and data compression ratio, following algorithms are adopted. In order to minimize encoding time, extension SAS being not searching of domain blocks is used. for reducing the bits per pixel, conventioal 4*4 range block is extended to 8*8 range block. and range block extension decrease quality of decoded image. For improvement quality of decoded image, the paper apply quad-tree partition mothod. In order to divide **8 range block, self-simiarity is compared 8*8 range block with spatial contractive transformed 8*8 domain block. According to self-simiarity, the block is partitioned and owing to block partition, increased encoding time is minimized. According to self-simiarity of 8*8 range block and spatial contractive transformed 8*8 domain block, number of fractal factor is varied. Simultaneously with minimizing the decrement of decoded image's quality, transmittion rate and encoding time is shorted. The results enable us to process the real-time fractal coding. For the claire test image, the average PSNR was 32.4dB, 0.12 bit rates and 33ms coding time per frame.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.7
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• pp.1654-1667
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• 1996

The conventional fractal image compression methods have high computational complexity at encoding reduce PSNR at low bit rate and havehighly visible blocking effects in a reconstructed image. In this paper we propose a fractal image compression method based on disctete wavelet transform domain, which takes the absolute value of discrete wavelet transform coefficient, and assembles the discrete wavelet tranform coefficients of different highpass subbands corresponding to the same spatial block and then applies "0" encoding according to the energy of each range blocks. The proposed method improved PSNR at low bit rate and reduced computational complexity at encoding distinctly. Also, this method can achieve a blockless reconstructed image and perform hierarchical decoding without recursive constractive transformation. Computer simulations with several test images show that the proposed method shows better performance than convnetional fractal coding methods for encoding still pictures. pictures.

• Molecules and Cells
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• v.27 no.4
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• pp.481-490
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• 2009

Diverse posttranslational modifications of histones, such as acetylation and methylation, play important roles in controlling gene expression. Histone methylation in particular is involved in a broad range of biological processes, including heterochromatin formation, X-chromosome inactivation, genomic imprinting, and transcriptional regulation. Recently, it has been demonstrated that proteins containing the Jumonji (Jmj) C domain can demethylate histones. In Arabidopsis, twenty-one genes encode JmjC domain-containing proteins, which can be clustered into five clades. To address the biological roles of the Arabidopsis genes encoding JmjC-domain proteins, we analyzed the temporal and spatial expression patterns of nine genes. RT-PCR analyses indicate all nine Arabidopsis thaliana Jmj (AtJmj) genes studied are actively expressed in various tissues. Furthermore, studies of transgenic plants harboring AtJmj::${\beta}$-glucuronidase fusion constructs reveal that these nine AtJmj genes are expressed in a developmentally and spatially regulated manner.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.917-924
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• 2008

Motion estimation and compensation in the spatial domain check the searching area of specified size in the previous frame and search block to minimize the difference with current block. When we check the searching area, it consumes the most encoding times due to increasing the complexity. We can solve this fault by means of motion estimation using shifting matrix in the transform domain instead of the spatial domain. We derive so the existed shifting matrix to a new recursion equation that we decrease more computations. We modify simply vertical shifting matrix and horizontal shifting matrix in the transform domain for motion estimation of half-pixel accuracy. So, we solve increasing computation due to bilinear interpolation in the spatial domain. Simulation results prove that motion estimation by the proposed algorithm in DCT-based transform domain provides higher PSNR using fewer bits than results in the spatial domain.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.691-700
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• 1995

Most fractal image codings using fractal concept require long encoding time because a large amount of computation is needed to find an optimal affine transformation point. Such a problem can be solved by designing a block classifier fitted to characteristics of image blocks. In general, it is possible to predict more precise and various types of blocks in frequency domain than in spatial domain. In this paper, we propose a block classifier to predict the block type using characteristics of DCT(Discrete Cosine Transform). This classifier has merits to enhance the quality of decoded images as well as to reduce the encoding time meeting fractal features. AC coefficient values in frequency domain make it possible to predict various types of blocks. As the results, the number of comparisons between a range block and the correspoding domain blocks to reach an optimal affine transformation point can be reduced. Specially, signs of DCT coefficients help to find the optimal affine transformation point with only two isometric transformations by eliminating unnecessary isometric transformations among eight isometric transformations used in traditional fractal codings.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.56-63
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• 2009

Nowdays, Most of Internet Contents delivered as a compressed file. It gives many advantages like deduction of communication bandwidth and transmission time etc. In case of JPEG Compression, Quantization is the most important procedure which accomplish the compression. In general signal processing, Quantization is the process which converts continuous analog signal to discrete digital signal. As you known already, Quantization over JPEG compression is to reduce magnitude of pixel value in spatial domain or coefficient in frequency domain. A lot of Data Hiding algorithms also developed to applicable for those compressed files. In this paper, we are going to unveil the influence of quantization table which used in the process of JPEG compression. Even thought most of algorithm modify frequency coefficients with considering image quality, they are ignoring the influence of quantization factor corresponding with the modified frequency coefficient. If existing algorithm adapt this result, they can easily evaluate their performances.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.11
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• pp.611-616
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• 2004

In this paper, we introduce a very fast and efficient fractal coding scheme by using the spatial prediction on ultra-small atomic range blocks. This new approach drastically speeds up the encoding while improving the fidelity and the compression ratio. The affine transformation coefficients between adjacent range blocks induced by this method often have good correlations thereby the compression ratios can further be improved. The proposed method leads to improved rate-distortion performance compared to previously reported pure fractals, and it is faster than other state-of-the-art fractal coding methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1860-1868
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• 1998

A simple postprocessing algorithm is proposed to reduce the blocky artifacts of Block Discrete Cosine Transform (BDCT) coded images. Since the block noise is mostly antisymmetric relative to the block boundaries, we model the blocky noise as one-dimensional antisymmertric functions made by superposing DCT basis functions. observing the frequency characteristics of the noies model, we approximate its high frequency components as those of step functions. Then the proposed postprocessing algorithm eliminates the carefully selected high frequency components of step functions in the one-dimensional sN-point DCT domain, when the encoding block size is $N\;{\times}\;N$. It is shown that the proposed algorithm can also be performed in the spatial domain without computational burden of transforms. The experimental results show that the proposed algorithm well reduces the blocky artifacts in both subjective and objectie viewpoints.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.507-513
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• 2006

In this paper, we propose an improved image encryption and fault-tolerance decryption method using phase wrapping and phase encoding in the frequency domain. To generate an encrypted image, an encrypting key which denotes the product of a phase-encoded virtual image, not an original image, and a random phase image is zero-padded and Fourier transformed and its real-valued data is phase-encoded. The decryption process is simply performed by performing the inverse Fourier transform for multiplication of the encrypted key with the decrypting key, made of the proposed phase wrapping method, in the output plane with a spatial filter. This process has the advantages of solving optical alignment and pixel-to-pixel mapping problems. The proposed method using the virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting from unauthorized people and also can be used as a current spatial light modulator technology by phase encoding of the real-valued data. Computer simulations show the validity of the encryption scheme and the robustness to noise of the encrypted key or the decryption key in the proposed technique.

• Journal of Information Processing Systems
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• v.15 no.1
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• pp.169-180
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• 2019

Transmitting visual information over a broadcasting network is not only prone to a copyright violation but also is a forgery. Authenticating such information and protecting its authorship rights call for more advanced data encoding. To this end, electronic watermarking is often adopted to embed inscriptive signature in imaging data. Most existing watermarking methods while focusing on robustness against degradation remain lacking of measurement against security loophole in which the encrypting scheme once discovered may be recreated by an unauthorized party. This could reveal the underlying signature which may potentially be replaced or forged. This paper therefore proposes a novel digital watermarking scheme in temporal-frequency domain. Unlike other typical wavelet based watermarking, the proposed scheme employed the Lorenz chaotic map to specify embedding positions. Effectively making this is not only a formidable method to decrypt but also a stronger will against deterministic attacks. Simulation report herein highlights its strength to withstand spatial and frequent adulterations, e.g., lossy compression, filtering, zooming and noise.