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Objective Edge Similarity Metric for denoising applications in MR images

Shanmugam Ashok, Rukmani Devi S.

Biocybernetics and Biomedical Engineering

2020

Vol. 40, no. 1

574--582

Edge Similarity Metrics (ESMs) are necessary to objectively quantify the inadvertent blur at the edge pixels which occurs during denoising. They are helpful for evaluating edge-preserving capability of nonlinear filters. Most of the ESMs in literature, consider similarity of either strength of the edges or their direction individually. They lag in terms of concordance with subjective edge similarity ratings. An Objective Edge Similarity Metric (OESM) which considers all three attributes of edges; strength, direction and width together, is proposed in this paper. Pearson's Correlation shown by Gradient Magnitude Similarity Deviation (GMSD), Gradient Similarity Measure (GSM), Edge Strength Similarity Index Metric (ESSIM) and OESM with Subjective Edge Similarity Score (SESS) are ˗0.9669 ± 0.0028, 0.9566 ± 0.0053, 0.9507 ± 0.0057 and 0.9848 ± 0.0038, respectively. OESM is able to measure the degree of edge similarity between images more efficiently than GMSD, GSM and ESSIM. It reflects the perceptual edge similarity between images more accurately than GMSD, GSM and ESSIM.

Adaptive shrinkage on dual-tree complex wavelet transform for denoising real-time MR images

Venuji Renuka Simi, Reddy Edla Damodar

Biocybernetics and Biomedical Engineering

2019

Vol. 39, no. 1

133--147

Performance of denoising filters which are based on the principle of wavelet thresholding greatly depends upon selection of the threshold value. An objective method is proposed in this paper for computing the optimum value of threshold in DTCWT based denoising. At optimum threshold, annoying intensity transitions of pixels in the homogeneous regions of the images, contributed by noise get completely suppressed and the true edges remain unaffected. For finding optimum value of threshold a newly derived quality metric termed as Optimum Denoising Index (ODI), which quantifies both the edge-preservation and smoothing of homogeneous regions is used. The ODI values corresponding to mean, median, Gaussian, Wiener, Bilateral, Kuwahara filters and wavelet thresholding are 0.1192±0.0118, 0.2196±0.0125, 0.1283±0.0118, 0.2106±0.0145, 0.1590±0.0331, 0.2200±0.0101 and 0.2516±0.0094, respectively. The wavelet thresholding has better edge-preservation and denoising capacity than the said denoising schemes. The ODI is highly correlated with its existing alternatives like Peak Signal to Noise Ratio (PSNR) and Structured Similarity Index Metric (SSIM) with values 0.9165 0.0536 and 0.9050 0.0452 respectively. This shows ODI is a good alternative to PSNR and SSIM.

Model segmentacji i wygładzania krawędzi w systemie do pomiaru kąta zwilżania i napięcia powierzchniowego

Wójcicki T.

Problemy Eksploatacji

2002

nr 2

255-264

W artykule przedstawiono wybrane metody obróbki i analizy obrazu zastosowane w programie komputerowym będącym elementem systemu pomiarowego urządzenia do pomiaru kąta zwilżania oraz napięcia powierzchniowego. Zaprezentowano wyniki wpływu doboru parametrów obróbki i analizy obrazów takich jak próg segmentacji oraz stopień wygładzania krawędzi na powtarzalność rezultatów wyznaczania kąta zwilżania i napięcia powierzchniowego. Opisano metody obróbki i analizy obrazów takie jak segmentacja i wygładzanie krawędzi.

The paper shows selected methods image processing and image analysis applied in computer program for measuring the contact angle and determining the interfacial tension of liquid. It presents results of influence parametars such as segmentation threshold and smoothing level on reproducibility of results of measuring the contact angle and determining the interfacial tension of liquid. It also describes image processing and image analysis methods such as segmentation and edge smoothing.