블록 기반의 2차원 리프팅 이산 웨이블릿 변환의 VLSI 구현

김송주 한국정보기술학회 2014 한국정보기술학회논문지 Vol. No.

In this paper, we proposed some improvements on VLSI implementation of lifting-based Daubechies 9/7 wavelet transform. The proposed structure used block-based scheme which removes blocking artifact and reduces internal memory usage for 2-D lifting Discrete Wavelet Transform(DWT). Also we optimized VLSI structure of this circuit by applying pattern search algorithm to lifting-based DWT filter to reduce hardware cost. We got enough PSNR results (average 48dB) from reconstructed images which are obtained through inverse wavelet transform in Matlab using hardware implemented wavelet transform processor output. The proposed structure of filter is suitable for video security with relatively small size and still image compression applications with low cost. 본 논문에서는 리프팅 기반의 Daubechies 9/7 웨이블릿 필터의 개선된 VLSI 구조를 제안하였다. 제안한 구조는 이차원 리프팅 DWT를 위해 타일링에 따른 왜곡이 없고 내부 메모리 사용이 적은 블록 기반 방식을 사용하였다. 또한 하드웨어 비용을 감소시키기 위해 패턴 탐색 기법의 알고리즘을 리프팅 기반의 DWT 필터에 적용하여 회로의 VLSI 구조를 최적화하였다. 하드웨어로 구현한 웨이블릿 변환 프로세서의 출력 결과를 매트랩에서 역 웨이블릿 변환하여 복원한 영상들로부터 평균 48 dB 정도의 충분한 PSNR(Peak Signal to Noise Ratio, 신호대 잡음 비) 결과를 얻었다. 본 논문에서 제안한 필터의 개선된 구조는 영상 보안과 같이 이미지의 크기가 상대적으로 작은 동영상과 정지영상 압축 응용분야에 낮은 구현 비용으로 적용하기에 적합하다고 하겠다.

영상의 에지 특성을 고려한 웨이블릿 기반의 적응적인 워터마킹 기법

이재혁(Jae-Hyuk Lee),문호석(Ho-Seok Moon),박상성(Sang-Sung Park),장동식(Dong-Sik Jang) 한국컴퓨터정보학회 2006 韓國컴퓨터情報學會論文誌 Vol.11 No.2

본문에서는 Discrete Wavelet Transform(DWT)를 기반으로 한 워터마킹 알고리즘을 제안하였다. 제안한 방법은 원 영상을 네 개의 영상으로 분할하고, 각 분할된 영상들을 2단계 DWT한다. 네 개의 DWT된 영상 중 하나의 영상에 에지 테이블(Edge Table) 이라는 새로운 개념으로 영상의 고유한 에지 특성을 고려해 워터마크를 삽입하였다. 워터마크 추출 시에는 워터마크가 삽입된 한 개의 분할 영상과 나머지 분할 영상들을 비교하여 원 영상 없이 워터마크를 추출하였다. 기존의 Blind 워터마킹의 문제점 중의 하나인 명암이 급격히 변하는 에지 영역에서의 부정확한 추정을 본 논문에서는 에지 테이블을 사용하여 극복하였다. 뿐만 아니라, 저주파(Low frequency) 영역에 워터마크를 삽입하여, 영상의 품질(Quality)를 유지하였고, 영상의 평가 방법인 PSNR 테스트 및 인간의 눈에서 느껴지는 주관적인 화질도 향상됨을 보였다. A discrete wavelet transform(DWT)-based image watermarking algoritmm is proposed in this paper. the proposed method decompose the original image into four subsampled images. Subsampled images are transformed by 2 level DWT, respectivelty. The proposed method embeds the watermark into one of the subsampled DWT images using edge table that represents dege chracteristics of the original image. Without an original image, a watermark is extracted through comparison one subsampled DWT image inserted the watermark with the rest of the submapled DWT images. many exiting methodes do not adequately estimate edge regions where intensities are changed abruptly. The proposed method address with an edge table. Also, even if the watermark is embedded into a low frequency area, our method preserves the image quality. The vality of the proposed method is demonstrated through the PSNR test and subjective image quality that human eyes feel.

Implementation of discrete wavelet transform-based discrimination and state-of-health diagnosis for a polymer electrolyte membrane fuel cell

Kim, J.,Tak, Y. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.20

This research investigates a new approach based on the discrete wavelet transform (DWT) that suitable for analyzing and evaluating output terminal voltage signal (OTVS) for discrimination analysis of a polymer electrolyte membrane fuel cell (PEMFC). Due to its ability for extracting information from the non-stationary and transient phenomena simultaneously in both time and frequency domain, the OTVS can be applied as source data in the DWT-based approach. By using the wavelet decomposition including the multi-resolution analysis (MRA) using the Daubechies wavelet (dB) as mother wavelet, the information on the electrochemical characteristics of a PEMFC can be extracted from the OTVS over a wide frequency range. Thus, the cells that have similar electrochemical characteristics can be eventually discriminated. In particular, this present research develops these investigations one step further by showing low-frequency components (approximation A<SUB>n</SUB>) and high-frequency components (detail D<SUB>n</SUB>) extracted from variable single cells with different electrochemical characteristics. Experimental results show that DWT-based approach is clearly appropriate for the reliable SOH diagnosis for a PEMFC.

Comparative Analysis of DWT and DWT-SVD Watermarking Techniques in RGB Images

Neha Narula,Deepak Sethi,Partha Pratim Bhattacharya 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.4

Digital watermarking is an application associated with copyright protection. Any digital object can be used as a carrier to carry information. If the information is related to object then it is known as a watermark which can be visible or invisible. In the era of digital information, there are multiple danger zones like copyright and integrity violation of digital object. In case of any dispute during violation, content creator can prove ownership by recovering the watermark. In this paper, a comparative study of two most recent digital watermarking techniques namely DWT and DWT-SVD over RGB images is presented. In case of DWT (Discrete Wavelet Transform) watermarking technique, decomposition of the original image is done to embed the watermark and in case of DWT-SVD watermarking technique, firstly original image is decomposed according to DWT and then watermark is embedded in singular values obtained by applying SVD (Singular Value Decomposition). The performances of the proposed techniques are compared on the basis of PSNR values.

Applications of Discrete Wavelet Analysis for Predicting Internal Quality of Cherry Tomatoes using VIS/NIR Spectroscopy

김기석,김대용,김건희,조병관 한국농업기계학회 2013 바이오시스템공학 Vol.38 No.1

Purpose: This study evaluated the feasibility of using a discrete wavelet transform (DWT) method as a preprocessing tool for visible/near-infrared spectroscopy (VIS/NIRS) with a spectroscopic transmittance dataset for predicting the internal quality of cherry tomatoes. Methods: VIS/NIRS was used to acquire transmittance spectrum data, to which a DWT was applied to generate new variables in the wavelet domain, which replaced the original spectral signal for subsequent partial least squares (PLS) regression analysis and prediction modeling. The DWT concept and its importance are described with emphasis on the properties that make the DWT a suitable transform for analyzing spectroscopic data. Results: The R2 values and root mean squared errors (RMSEs) of calibration and prediction models for the firmness, sugar content, and titratable acidity of cherry tomatoes obtained by applying the DWT to a PLS regression with a set of spectra showed more enhanced results than those of each model obtained from raw data and mean normalization preprocessing through PLS regression. Conclusions: The developed DWT-incorporated PLS models using the db5 wavelet base and selected approximation coefficients indicate their feasibility as good preprocessing tools by improving the prediction of firmness and titratable acidity for cherry tomatoes with respect to R2 values and RMSEs.

Applications of Discrete Wavelet Analysis for Predicting Internal Quality of Cherry Tomatoes using VIS/NIR Spectroscopy

Kim, Ghiseok,Kim, Dae-Yong,Kim, Geon Hee,Cho, Byoung-Kwan Korean Society for Agricultural Machinery 2013 바이오시스템공학 Vol.38 No.1

Purpose: This study evaluated the feasibility of using a discrete wavelet transform (DWT) method as a preprocessing tool for visible/near-infrared spectroscopy (VIS/NIRS) with a spectroscopic transmittance dataset for predicting the internal quality of cherry tomatoes. Methods: VIS/NIRS was used to acquire transmittance spectrum data, to which a DWT was applied to generate new variables in the wavelet domain, which replaced the original spectral signal for subsequent partial least squares (PLS) regression analysis and prediction modeling. The DWT concept and its importance are described with emphasis on the properties that make the DWT a suitable transform for analyzing spectroscopic data. Results: The $R^2$ values and root mean squared errors (RMSEs) of calibration and prediction models for the firmness, sugar content, and titratable acidity of cherry tomatoes obtained by applying the DWT to a PLS regression with a set of spectra showed more enhanced results than those of each model obtained from raw data and mean normalization preprocessing through PLS regression. Conclusions: The developed DWT-incorporated PLS models using the db5 wavelet base and selected approximation coefficients indicate their feasibility as good preprocessing tools by improving the prediction of firmness and titratable acidity for cherry tomatoes with respect to $R^2$ values and RMSEs.

A Model to Predict the Strength of Watermark in DWT-Based Image Watermarking

Ho Seok Moon,Suk Bong Park,Hyun Wung Bae 한국데이터정보과학회 2008 한국데이터정보과학회지 Vol.19 No.2

One of main issues in watermarking is to resolve the strength of watermark for solving the problem of trade-off between fidelity and robustness of watermarking. In the previous research, the strength of watermark has been resolved fixed value generally without considering local image characteristics such as image brightness, contrast, and edge. This paper proposes a new model to predict the strength of watermark considering local image characteristics such as image brightness, contrast, and edge for digital wavelet transform(DWT)-based image watermarking. For the study, psychological experiment was fulfilled to measure the human image perception and regression analysis showed the proposed model was statistically significant at the level of α = 0.01. Also the model is practically validated on fidelity and robustness of watermarking.

Comparative Analysis of the DWT-based Denoising Technique Selection in Noise-Riding DCV of the Li-Ion Battery Pack

Jonghoon Kim,Chang-Yoon Chun,B. H. Cho 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The noise-riding discharging/charging voltage (DCV) of the Li-Ion battery pack may result in erroneous equivalent circuit model (ECM)-based state-of-charge (SOC) estimation and state-of-health (SOH) prediction of the Li-Ion battery pack. Namely, the noisy DCV is intimately linked with a low battery management system (BMS) performance. Therefore, additional technique should be absolutely required for noise reduction of the DCV. This work presented an implementation of the discrete wavelet transform (DWT)-based denoising technique that enables us to provide the de-noised DCV. Specifically, this work develops prior investigation one step further by performing a comparative analysis of the DWT-based denoising technique that uses different thresholding methods such as hard- and soft-thresholding. With regard to the denoising technique using hard-thresholding that retains a small number of coefficients, it is inevitable that the results are often smoothed at the expense of loosing information of the DCV. On the other hand, it is possible to acquire an improved noise-reduction of the DCV through the denoising technique using soft-thresholding retaining a large number of coefficients. Finally, selection of the proper thresholding method is a significant task in determining the signal-to-noise ratio (SNR), and analytic results indicate the clear comparison by showing the SNR difference between two denoising techniques considering hard- and soft-thresholding. For reference, threshold value has been calculated by VisuShrink method.

A Model to Predict the Strength of Watermark in DWT-Based Image Watermarking

문호석,박석봉,배현웅 한국데이터정보과학회 2008 한국데이터정보과학회지 Vol.19 No.2

One of main issues in watermarking is to resolve the strength of watermark for solving the problem of trade-off between fidelity and robustness of watermarking. In the previous research, the strength of watermark has been resolved fixed value generally without considering local image characteristics such as image brightness, contrast, and edge. This paper proposes a new model to predict the strength of watermark considering local image characteristics such as image brightness, contrast, and edge for digital wavelet transform(DWT)-based image watermarking. For the study, psychological experiment was fulfilled to measure the human image perception and regression analysis showed the proposed model was statistically significant at the level of α = 0.01. Also the model is practically validated on fidelity and robustness of watermarking.

태양광 직렬 아크 검출기의 오검출 방지를 위한 DWT 기반 파라미터 및 반복 알고리즘

안재범,이진한,이진,류홍제,Ahn, Jae-Beom,Lee, Jin-Han,Lee, Jin,Ryoo, Hong-Je 전력전자학회 2022 전력전자학회지 Vol.27 No.2

This paper applies the arc detection algorithm to prevent the false detection in photo voltaic series arc detection circuit, which is required not only to detect the series arc quickly, but also not falsely detect the arc for the non-arc noise. For this purpose, this study proposes a rapid and preventive false detection method of single peak noise and short noise signals. First, to prevent false detection by single peak noise, Discrete wavelet transform (DWT)-based characteristic parameters are applied to determine the shape and the amplitude of the noise. In addition, arc fault detection within a few milliseconds is performed with the DWT iterative algorithm to quickly prevent false detection for short noise signals, considering the continuity of serial arc noise. Thus, the method operates not only to detect series arc, but also to avoid false arc detection for peak and short noises. The proposed algorithm is applied to real-time serial arc detection circuit based on the TMS320F28335 DSP. The serial arc detection and peak noise filtering performances are verified in the built simulated arc test facility. Furthermore, the filtering performance of short noise generated through DC switch operation is confirmed.