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RISS 인기검색어
- 검색키워드
- 저자 : Nagashettappa Biradar (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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A Novel Hybrid Homomorphic Fuzzy Filter for Speckle Noise Reduction
Nagashettappa Biradar,M. L. Dewal,Manoj Kumar Rohit 대한의용생체공학회 2014 Biomedical Engineering Letters (BMEL) Vol.4 No.2
Purpose The presence of speckle noise and artifacts makedelineation of transthoracic echocardiographic (TTE) imagesquite difficult and challenging; the edges are to be preservedwhile removing noise. To address issues, a novel specklereduction technique is being proposed and analyzed. Methods Three fuzzy filters based on median and movingaverage concepts are experimented in homomorphic domainand the best one is further fine tuned for applications on TTEimages. The proposed hybrid homomorphic Fuzzy (HHF)filter is the sequential integration of homomorphic fuzzyfilter with anisotropic diffusion. The denoising characteristicsof HHF filter are compared with ten existing techniquestested in homomorphic and other seven in non-homomorphicdomain using seven different performance parameters alongwith visual quality assessment. Experimentations are performedon TTE images acquired in two parasternal and three apicalviews, since image in one view may not very precisely speakof underlying valvular abnormality. Results The edge preservation capability is increased bymany fold (around 8 times) upon integration of homomorphicfuzzy filter with the anisotropic diffusion filtering technique. Beta metric, figure of merit and structure similarity indicesare all greater than 0.97 for proposed HHF filter. Conclusions The performance of proposed HHF filter issuperior in comparison to seventeen state-of-art denoisingtechniques in terms of all seven performance parameters. Noise is reduced with the edges and structure of TTE imageswell preserved.
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Comparative Analysis of Despeckling Filters for Continuous Wave Doppler Images
Nagashettappa Biradar,Mohan Lal Dewal,Manoj Kumar Rohit 대한의용생체공학회 2015 Biomedical Engineering Letters (BMEL) Vol.5 No.1
Purpose The problems of speckle noise, low contrast, andother artifacts in continuous wave Doppler (CWD) basedechocardiographic images are identical to the issues prevailingin the B-mode images. The median filter and Gaussian lowpass filter are more commonly used for reduction of noise inCWD images. The applications of state-of-the-art despecklingfilters and their impact on delineation are not extensivelyanalyzed using CW Doppler images. Methods This paper analyses the noise reduction, edge andstructure preservation characteristics of ten filters for CWDimages in terms of 15 image quality metrics along with visualquality assessment. Further, three segmentation techniqueswere analyzed using original and noisy CWD images. Threeexisting delineation techniques are modified for tracing theouter boundaries of CWD spectrum. The Gaussian filter usedreaction-diffusion based active contour and thresholdingbased segmentation techniques are replaced by despecklingfilter based on anisotropic diffusion and local statistics. Results The noise is suppressed with edges and structurewell preserved on application of filters such as specklereducing anisotropic diffusion filter and local statics (meanand variance) based filter. The number of iterations requiredin complete boundary tracing is reduced on replacing theGaussian filter with despeckling filter in reaction diffusionbased active contour segmentation. Conclusions The analysis reveals that the despecklingtechniques enhance the visual quality of images and play avital role in delineation process. The reaction diffusion basedactive contour embedded with speckle reducing anisotropicdiffusion filter results in accurate contouring of the CWDimages.
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