نتایج جستجو برای: speckle redaction

تعداد نتایج: 9100  

2016
António J. Pereira Paulo Aguiar Michael Belsley Helder Maiato

The understanding of cytoskeleton dynamics has benefited from the capacity to generate fluorescent fiducial marks on cytoskeleton components. Here we show that light-induced imprinting of three-dimensional (3D) fluorescent speckles significantly improves speckle signal and contrast relative to classic (random) fluorescent speckle microscopy. We predict theoretically that speckle imprinting usin...

2013
R. Balamurugan S. Muruganand

Digital speckle image correlation techniques have been successfully proven to be an accurate displacement analysis tool for a wide range of applications. In this paper, a new Electronic Laser Speckle Pattern Interferometer based on Michelson interferometer is designed. An object beam back scattered of an object surface and a reference beam, originating from the same laser light source are super...

Journal: :Journal of biomedical optics 2012
Gijs van Soest Martin Villiger Evelyn Regar Guillermo J Tearney Brett E Bouma Antonius F W van der Steen

Quantitative analysis of optical coherence tomography data can be strongly hampered by speckle. Here, we introduce a new method to reduce speckle, which leverages from Fourier-domain configurations and operates on individual axial scans. By subdividing the digitized spectrum into a number of distinct narrower windows, each with a different center frequency, several independent speckle patterns ...

1997
C. A. Thompson K. J. Webb A. M. Weiner

We present a method for the detection and localization of inhomogeneities embedded within highly scattering media that employs speckle statistics with a partially coherent light source. Variations in speckle contrast as a function of position are used to interrogate inhomogeneities deeply embedded within scattering media. A numerical model based on photon diffusion theory is introduced to predi...

2013
Jonathan Maycock John B. McDonald Bryan M. Hennelly

We report on a new digital signal processing technique that reduces speckle in reconstructions of digital holograms. This is achieved by convolving the three dimensional intensity pattern (the intensity of the propagated DH at a series of different distances) with a 3D point spread function in all three dimensions (x,y,z ). It is based on the fact that the addition of different independent spec...

Journal: :Biomedical optics express 2013
J C Ramirez-San-Juan E Mendez-Aguilar N Salazar-Hermenegildo A Fuentes-Garcia R Ramos-Garcia B Choi

Laser Speckle Contrast Imaging (LSCI) is an optical technique used to generate blood flow maps with high spatial and temporal resolution. It is well known that in LSCI, the speckle size must exceed the Nyquist criterion to maximize the speckle's pattern contrast. In this work, we study experimentally the effect of speckle-pixel size ratio not only in dynamic speckle contrast, but also on the ca...

Journal: :Computerized medical imaging and graphics : the official journal of the Computerized Medical Imaging Society 2007
Stavros Tsantis Nikos Dimitropoulos M. Ioannidou Dionisis A. Cavouras George Nikiforidis

A wavelet-based method for speckle suppression in ultrasound images of the thyroid gland is introduced. The classification of image pixels as speckle or part of important image structures is accomplished within the framework of back-propagation tracking and singularity detection of wavelet transform modulus maxima, derived from inter-scale analysis. A comparative study with other de-speckling t...

Mohammad R. N. Avanaki Mohammad R. Pishgoo Reza Ebrahimpour

Optical Coherence Tomography (OCT) uses the spatial and temporal coherence properties of optical waves backscattered from a tissue sample to form an image. An inherent characteristic of coherent imaging is the presence of speckle noise. In this study we use a new ensemble framework which is a combination of several Multi-Layer Perceptron (MLP) neural networks to denoise OCT images. The noise is...

2009
Bo Wang Tian Cao Yuguo Dai Dong C. Liu

Recently, some diffusion-based filtering methods have been developed such as anisotropic diffusion (AD) or nonlinear diffusion (ND), which can reduce the speckle noise, at the same time, preserve and enhance the edge/borders in ultrasound image. However, because of the granular pattern of speckle, it is quite difficult to reduce speckle exactly through diffusion-based methods only. In this pape...

2005
D. Ambrosini

Optical techniques have a long tradition in studying flow phenomena. In particular, speckle photography, introduced in 1968, has been extensively used. White-light speckle photography has certain advantages with respect to traditional speckle photography, which makes it a more robust method. The aim of this work is to evaluate quantitatively advantages and disadvantages of the technique using b...

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