• Journal of the Korea Society of Computer and Information
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• v.4 no.2
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• pp.141-146
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• 1999

In this paper, picture set filter is proposed for preserving compression ratio and video qualify. This filter controls the compression ratio of each frame depending on the correlation to the reference frame by selectively eliminating less important high-resolution areas. Consequently, video quality can be preserved and bit rate can be controlled adaptively. In the simulation, to test the performance of the proposed coding method, comparisons with the full search block matching algorithm and the differential image coding algorithm are made. In the former case, video quality, compression ratio and encoding time is improved. In the latter case, video quality is degraded, but compression ratio and encoding time is improved. Consequently. the proposed method shows a reasonably good performance over existing ones.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.1-7
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• 2004

The rapid growth of digital media and communication networks has created an urgent need for self-contained data identification methods to create adequate intellectual property right(IPR) protection technology. In this paper we propose a new watermarking method that could embed the gray-scale watermark logo in low frequency coefficients of discrete wavelet transform(DWT) domain as the marking space by using our Linear Bit-eXpansion(LBX) interleaving of gray-scale watermark, to use lots of watermark information without distortion of watermarked image quality and particularly to be robust against attack which could remove a part of image. Experimental results demonstrated the high robustness in particular against attacks such as image cropping and rotation which could remove a part of image.

• Proceedings of the KIEE Conference
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• summer
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• pp.607-609
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• 2004

A breakdown occurred in power transformer causes interruption of power transmission. Protective relay should be installed in transformer to detect such a fault. Protective relaying algorithm for transformer must be included a function to discriminate between winding fault and inrushing state. Recently, current differential relay is widely used to protect power transformer. However if inrush occurs in transformer, relay can be tripped by judging as internal fault. New algorithms are required in order to such problem. This study proposes a new protective relaying algorithm using Neuro-Fuzzy inference and wavelet. A variety of transformer transient states are simulated by BCTRAN and HYSDT in EMTP. D1 coefficients of differential current are obtained by wavelet transform. D1 coefficients and RMS of 3-phase primary voltage are used to make a target data and are trained by Nwo-Fuzzy algorithm which distinguishes correctly whether internal fault occurs or not within 1/2 after fault detection. It is evaluated that the results obtained by simulations can effectively protect a transformer by contact discriminating between winding fault and inrushing state.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.3
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• pp.45-52
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• 2000

In this study, we propose the image segmentation algorithm for facial region segmentation. The proposed algorithm separates the mean image of low frequency band from the differential image of high frequency band in order to make a boundary using HWT, and then we reduce the isolation pixels, projection pixels, and overlapped boundary pixels from the low frequency band. Also the boundaries are detected and simplified by the proposed boundary detection algorithm, which are cleared on the thinning process of 1 pixel unit. After extracting facial image boundary by using the proposed algorithm, we make the mask and segment facial image through matching original image. In the result of facial region segmentation experiment by using the proposed algorithm, the successive facial segmentation have 95.88% segmentation value.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.1
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• pp.171-181
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• 2012

This paper introduces the double-density discrete wavelet transform(DWT) using quincunx sampling, which is a DWT that combines the double-density DWT and quincunx sampling method, each of which has its own characteristics and advantages. The double-density DWT is an improvement upon the critically sampled DWT with important additional properties: Firstly, It employs one scaling function and two distinct wavelets, which are designed to be offset from one another by one half. Secondly, the double-density DWT is overcomplete by a factor of two, and Finally, it is nearly shift-invariant. In two dimensions, this transform outperforms the standard DWT in terms of denoising; however, there is room for improvement because not all of the wavelets are directional. That is, although the double-density DWT utilizes more wavelets, some lack a dominant spatial orientation, which prevents them from being able to isolate those directions. A solution to this problem is a quincunx sampling method. The quincunx lattice is a sampling method in image processing. It treats the different directions more homogeneously than the separable two dimensional schemes. Proposed wavelet transformation can generate sub-images of multiple degrees rotated versions. Therefore, This method services good performance in image processing fields.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.237-247
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• 2014

This paper describes a 2D discrete-time wavelet transform for which the Q-factor is easily specified. Hence, the transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. The tunable Q-factor wavelet transform (TQWT) is a fully-discrete wavelet transform for which the Q-factor, Q, of the underlying wavelet and the asymptotic redundancy (over-sampling rate), r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The TQWT can also be used as an easily-invertible discrete approximation of the continuous wavelet transform. The transform is based on a real valued scaling factor (dilation-factor) and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its oversampling rate (redundancy), with modest oversampling rates (e. g. 3-4 times overcomplete) being sufficient for the analysis/synthesis functions to be well localized. Therefore, This method services good performance in image processing fields.

• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.3-15
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• 2000

In this paper we present a new image denoising filter that can suppress additive noise components while preserving signal components in the wavelet domain. The proposed filter, which we call an adaptive wavelet shrinkage(AWS) filter, is composed of two operators: the wavelet killing operator and the adaptive shrinkage operator. Each operator is selected based on the threshold value which is estimated adaptively by using the local statistics of the wavelet coefficients. In the wavelet killing operation, the small wavelet coefficients below the threshold value are replaced by zero to suppress noise components in the wavelet domain. The adaptive shrinkage operator attenuates noise components from the wavelet components above the threshold value adaptively. The experimental results show that the proposed filter is more effective than the other methods in preserving signal components while suppressing noise.

• Journal of Korea Multimedia Society
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• v.4 no.6
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• pp.500-509
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• 2001

Image compression based on Wavelet gives much better quality than JPEG based on DCT, but suffers from ringing or blurring effects around edges as the compression is increased. In this paper, we proposed enhanced image compression by pre-processing wavelet coefficients. This pre-processing is performed by making a low threshold and enhanced by zerotree scan method when subband's zerotrees are established. It might increase significants coefficient by means of modifying the threshold and reflect on the orientation of subbands. Some experimental results show our method is more efficient than the conventional methods, JPEG. And then the developed coding scheme improves the quality of images and visually shows more pleasing results for most practical images.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.2
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• pp.41-49
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• 2016

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the author propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the lifting wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.