Defocused Image Restoration Using Translation Invariant Wavelet Transform

2006 ◽  
Author(s):  
Hisanaga Fujiwara ◽  
Zhong Zhang ◽  
Tetsuo Miyake
Keyword(s):  
Wavelet Transform ◽  
Image Restoration ◽  
Translation Invariant ◽  
Defocused Image

RL turbulence degraded image restoration algorithm based on wavelet transform

2017 ◽  
Vol 32 (10) ◽  
pp. 822-827
Author(s):  
徐晓睿 XU Xiao-rui ◽  
戴 明 DAI Ming ◽  
尹传历 YIN Chuan-li
Keyword(s):  
Wavelet Transform ◽  
Image Restoration ◽  
Restoration Algorithm ◽  
Degraded Image

Genetic algorithm based automated threshold estimation in translation invariant wavelet transform for denoising PD signal

2015 ◽  
Vol 34 (4) ◽  
pp. 1252-1269 ◽  
Author(s):  
R.V. Maheswari ◽  
B. Vigneshwaran ◽  
L. Kalaivani
Keyword(s):  
Genetic Algorithm ◽  
Wavelet Transform ◽  
Computational Complexity ◽  
Condition Monitoring ◽  
Random Noise ◽  
Life Time ◽  
Discrete Wavelet ◽  
Statistical Parameters ◽  
Translation Invariant ◽  
Content Type

Purpose – The purpose of this paper is to investigate the condition of insulation in high-voltage equipments using partial discharge (PD) measurements. It proposes the methods to eliminate several noises like white noise, random noise and discrete spectral interferences which severely pollutes the PD signals. The study aims to remove these noises from the PD signal effectively by preserving the signal features. Design/methodology/approach – This paper employs fast Fourier transform, discrete wavelet transform and translational invariant wavelet transform (TIWT) for denoising the PD signals. The simulated damped exponential pulse and damped oscillatory pulse with low- and high-level noises and a measured PD signal are considered for this analysis. The conventional wavelet denoising approach is also improved by estimating the automated global optimum threshold value using genetic algorithm (GA). The statistical parameters are evaluated and compared. Among these methods, GA-based TIWT approach provides robustness and reduces computational complexity. Findings – This paper provides effective condition monitoring of power apparatus using GA-based TIWT approach. This method provides the low value of mean square error, pulse amplitude distortion and also high reduction in noise level due to its robustness and reduced computational complexity. It suggests that this approach works well for both signals immersed in noise as well as for noise immersed in signals. Research limitations/implications – Because of the chosen PD signals, the research results may lack for multiple discharges. Therefore, researchers are encouraged to test the proposed propositions further. Practical implications – The paper includes implication for the development of online testing for equipment analysis and diagnostics during normal operating condition. Corrective actions can be planned and implemented, resulting in reduced unscheduled downtime. Social implications – This PD-based analysis often present well in advance of insulation failure, asset managers can monitor it over time and make informed strategic decisions regarding the repair or replacement of the equipment. These predictive diagnostics help society to prioritize investments before an unexpected outage occurs. Originality/value – This paper provides an enhanced study of condition monitoring of HV power apparatus by which life time of insulation can be increased by taking preventive measures.

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