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Simultaneous Blood Flow Measurement and Dermoscopy of Skin Lesions Using Dual-Mode Dermascope
摘要： Dermascopes are commonly utilized for the qualitative visual inspection of skin lesions. While automated image processing techniques and varied illumination strategies have been used to aid in structural analysis of lesions, robust quantification of functional information is largely unknown. To address this knowledge gap, we have developed a compact, handheld dermascope that enables real-time blood flow measurements of skin during conventional visual inspection. In-vitro characterization demonstrated that the dermascope is capable of quantifying changes in flow across a physiologically relevant range even when used in a handheld manner with clinic lighting and dermascope LEDs on. In a small pilot clinical study, we demonstrated the dermascope’s ability to detect flow differences between two distinct lesion types.
关键词： Skin Lesions,Laser Speckle Contrast Imaging,Functional Information,Dermoscopy,Blood Flow Measurement
更新于2025-09-11 14:15:04
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Residual Stress Analysis Based on Acoustic and Optical Methods
摘要： Co-application of acoustoelasticity and optical interferometry to residual stress analysis is discussed. The underlying idea is to combine the advantages of both methods. Acoustoelasticity is capable of evaluating a residual stress absolutely but it is a single point measurement. Optical interferometry is able to measure deformation yielding two-dimensional, full-field data, but it is not suitable for absolute evaluation of residual stresses. By theoretically relating the deformation data to residual stresses, and calibrating it with absolute residual stress evaluated at a reference point, it is possible to measure residual stresses quantitatively, nondestructively and two-dimensionally. The feasibility of the idea has been tested with a butt-jointed dissimilar plate specimen. A steel plate 18.5 mm wide, 50 mm long and 3.37 mm thick is braze-jointed to a cemented carbide plate of the same dimension along the 18.5 mm-side. Acoustoelasticity evaluates the elastic modulus at reference points via acoustic velocity measurement. A tensile load is applied to the specimen at a constant pulling rate in a stress range substantially lower than the yield stress. Optical interferometry measures the resulting acceleration field. Based on the theory of harmonic oscillation, the acceleration field is correlated to compressive and tensile residual stresses qualitatively. The acoustic and optical results show reasonable agreement in the compressive and tensile residual stresses, indicating the feasibility of the idea.
关键词： electronic speckle-pattern interferometry,residual stress analysis,acoustoelasticity,scanning acoustic microscopy
更新于2025-09-10 09:29:36
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Microscopic Three-Dimensional Measurement Based on Telecentric Stereo and Speckle Projection Methods
摘要： Three-dimensional (3D) measurement of microstructures has become increasingly important, and many microscopic measurement methods have been developed. For the dimension in several millimeters together with the accuracy at sub-pixel or sub-micron level, there is almost no effective measurement method now. Here we present a method combining the microscopic stereo measurement with the digital speckle projection. A microscopy experimental setup mainly composed of two telecentric cameras and an industrial projection module is established and a telecentric binocular stereo reconstruction procedure is carried out. The measurement accuracy has ?rstly been veri?ed by performing 3D measurements of grid arrays at different locations and cylinder arrays with different height differences. Then two Mitutoyo step masters have been used for further veri?cation. The experimental results show that the proposed method can obtain 3D information of the microstructure with a sub-pixel and even sub-micron measuring accuracy in millimeter scale.
关键词： microscopic measurement,telecentric cameras,stereo vision,speckle projection
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Sar Speckle Filtering by Improved INLP Filter
摘要： The filtered pixels of the infinite number of looks prediction (INLP) filter are determined by the application of a linear regression between means and variances for various window sizes. In this paper, we improved the performance of the INLP filter in terms of versatility, computing complexity, speckle reduction and spatial detail preservation by adapting the parameter Nmin which is the key parameter to scene variability. Results show that the improved INLP outperformed the improved sigma filter, the non-local filter and the original INLP filter.
关键词： SAR,INLP filter,speckle,MMSE filter
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - An Adaptive Multilooking Scheme for Multi-Temporal Insar Data
摘要： Multilooking is an effective speckle reduction tool for InSAR images. However, it has some limitations. Based on the De-specKS and NL-SAR algorithms, an adaptive multilooking scheme for multi-temporal InSAR data has been proposed in this paper. Simulated and real SAR datasets have been employed to evaluate the performance of this scheme. The results show that, by taking advantages of DespecKS and NL-SAR, the proposed scheme presents better detail preservation and speckle noise reduction performances comparing with these two advanced and classical multilooking algorithms.
关键词： Speckle noise reduction,multi-temporal InSAR data,NL-SAR,DespecKS,adaptive multi-looking
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - An Adaptive Region-Based Method for Speckle Reduction in SAR Images with Local Geometric Correlation
摘要： For adaptive region-based despeckling methods, the shape of the adaptive region is of large influence on the estimation of the true value. In this paper, given the effectiveness of patch-based index on measuring the relativity of samples, an adaptive region is formed at each pixel via the patch-based index where the local geometric correlation (such as the anisotropy and the compactness) among the pixels in the patch is explored as an Adaptive Kernel (AK) function. Then, using all pixels contained in the adaptive region, Maximum likelihood rule is adopted to estimate the true value of the concerned pixel. From the experimental results on real and synthetic SAR images, by using the AK function embedded patchy index to determine the adaptive region, not only the speckle is largely reduced, but also the resolution of the details is well preserved by our method.
关键词： adaptive region,patch-based index,local geometric correlation,speckle reduction,SAR imagery
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Performance Analysis of Speckle Filtering on Single-Look Polsar Data for Land Cover Classification
摘要： The speckle ?ltering is an essential preprocessing step of polarimetric SAR (PolSAR) data processing. The PolSAR speckle ?lters perform generally better on multilook datasets. The multilooking is performed to reduce speckle and improve parameter estimation but it also degrades resolution of the datasets. The speckle ?ltering after multilooking further degrades the resolution. The analysis on suitability of speckle ?ltering algorithms for single-look data is absent in the literature. In this paper, state-of-the-art PolSAR speckle ?lters are analyzed for the single-look PolSAR data. The single-look Monte Carlo simulated and real RADARSAT-2 PolSAR data are used for performance analysis.
关键词： SAR,polarimetric,Monte Carlo simulation,?ltering,Speckle
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Learning Speckle Suppression in Sar Images Without Ground Truth: Application to Sentinel-1 Time-Series
摘要： This paper proposes a method of denoising SAR images, using a deep learning method, which takes advantage of the abundance of data to learn on large stacks of images of the same scene. The approach is based on the use of convolutional networks, used as auto-encoders. Learning is led on a large pile of images acquired on the same area, and assumes that the images of this stack differ only by the speckle noise. Several pairs of images are chosen randomly in the stack, and the network tries to predict the slave image from the master image. In this prediction, the network cannot predict the noise because of its random nature. Also the application of this network to a new image fulfills the speckle filtering function. Results are given on Sentinel1 images. They show that this approach is qualitatively competitive with literature.
关键词： SAR,deep learning,speckle filtering
更新于2025-09-10 09:29:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - A Speckle Reduction Model for Sar Images Based on Beltrami Regularization
摘要： A novel variational model is proposed to remove the multiplication noise in the synthetic aperture radar (SAR) images to provide a high quality of interpretation of SAR data. The model consists of the data fidelity term and Beltrami regularization term. The former ensures the convexity of the model and avoids the nonlinear image transformation. The latter restrains the staircase-like artifacts caused by total variation (TV) regularization and preserves the geometric structure of the image effectively. Experiments on both synthetic and real SAR data demonstrate that, compared with three state-of-the-art methods, the proposed method achieves competitive results both visually and quantitatively.
关键词： Beltrami regularization,speckle noise,SAR images
更新于2025-09-10 09:29:36
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BIAS COMPENSATION IN H/A/α POLARIMETRIC SAR DECOMPOSITION AND ITS IMPLICATION FOR THE CLASSIFICATION
摘要： Classification of land cover types is one important application of polarimetric synthetic aperture radar (PolSAR) remote sensing. There are numerous features that can be extracted from PolSAR images. Among them, eigenvalues λi, entropy H, alpha angle α, and anisotropy A are effective and popular tools for the analysis and quantitative estimation of the physical parameters. Nevertheless, the speckle noise appearing in PolSAR images reduces the accuracy of image classification. Consequently, it should be filtered correctly. Generally, filtering PolSAR data generate biased estimates of λi/H/A/α parameters. In this paper, we studied the effects of bias compensation on supervised and unsupervised PolSAR image classification. We applied the asymptotic quasi maximum likelihood estimator AQ-MLE and Yahia/Aguili’s bias compensation methods. To improve the classification accuracies, we demonstrated that bias compensation must be associated with speckle reduction. The combination of the span with biased parameters reduced the effects of bias but did not eliminate it totally. Simulated and real data were used for validation.
关键词： Polarimetric SAR,speckle noise,eigendecomposition,bias compensation,classification
更新于2025-09-10 09:29:36