Results 301 to 310 of about 1,689,718 (367)
Some of the next articles are maybe not open access.
Time Reversal of Speckle Noise
Physical Review Letters, 2011Focusing a wave in an unknown inhomogeneous medium is an open problem in wave physics. This work presents an iterative method able to focus in pulse-echo mode in an inhomogeneous medium containing a random distribution of scatterers. By performing a coherent summation of the random echoes backscattered from a set of points surrounding the desired focus,
Gabriel, Montaldo +2 more
openaire +2 more sources
2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 2017
Speckle removal from single-channel and multi-dimensional SAR remains a difficult problem. In this paper, we are investigating the use of a Convolutional Neural Network (CNN), previously applied to the Super-Resolution problem, for speckle removal. Because speckle noise statistics is signal dependent, we are training the neural network on the residual ...
S. Foucher +3 more
openaire +1 more source
Speckle removal from single-channel and multi-dimensional SAR remains a difficult problem. In this paper, we are investigating the use of a Convolutional Neural Network (CNN), previously applied to the Super-Resolution problem, for speckle removal. Because speckle noise statistics is signal dependent, we are training the neural network on the residual ...
S. Foucher +3 more
openaire +1 more source
Journal of the Optical Society of America, 1976
A theory is presented which relates the minimum detectable contrast level for an object in the presence of noise to the statistics of the speckle. Consideration is given to smoothing of the noise by multiple looks and by area. Measurements of the minimum detectable contrast are made for two types of speckle noise. First, a coherent, plane wave is added
Nicholas George +3 more
openaire +1 more source
A theory is presented which relates the minimum detectable contrast level for an object in the presence of noise to the statistics of the speckle. Consideration is given to smoothing of the noise by multiple looks and by area. Measurements of the minimum detectable contrast are made for two types of speckle noise. First, a coherent, plane wave is added
Nicholas George +3 more
openaire +1 more source
Laser vibrometer speckle-noise cancellation
Measurement Science and Technology, 1993When a rotating scattering disc is used to frequency-shift the reference beam of a laser vibrometer, the noise floor is determined by speckle noise. The speckle noise is cancelled by recording it in the absence of target vibration and then subtracting the recorded signal Vr from that obtained when measuring the vibration. Vr is the average for 256 disc
T H Wilmshurst, N A Halliwell
openaire +1 more source
Speckle Noise Removal Using Contourlets
2006 International Conference on Information and Automation, 2006Speckle noise affects all coherent imaging systems including medical ultrasound. In medical images, noise suppression is a particularly delicate and difficult task. A trade off between noise reduction and the preservation of actual image features has to be made in a way that enhances the diagnostically relevant image content.
Latha Parthiban, R. Subramanian
openaire +1 more source
Radar speckle: noise or information?
IGARSS '96. 1996 International Geoscience and Remote Sensing Symposium, 2002The authors examine radar speckle from a non-traditional perspective. Instead of viewing radar speckle as noise, they attempt to assess the information content of radar speckle. A speckle identification algorithm is developed to separate speckle from pixels of "normal" returns. The relationships between land cover types and the density and roughness of
null Zong-Guo Xia, null Yongwei Sheng
openaire +1 more source
Speckle-Noise-Invariant Convolutional Neural Network for SAR Target Recognition
IEEE Geoscience and Remote Sensing Letters, 2019Speckle noise is inherent to synthetic aperture radar (SAR) images and degrades the target recognition performance. Deep learning based on convolutional neural networks (CNNs) has been widely applied for SAR target recognition, but the extracted features
Youngchul Kwak +2 more
semanticscholar +1 more source
Techniques For Speckle Noise Removal
Optical Engineering, 1981In this paper, several techniques to reduce speckle noise (more generally signal independent multiplicative noise) in images are studied. The techniques include gray scale modification, frame averaging, low-pass filtering in the intensity and density domains, and application of the short space spectral subtraction image restoration technique in the ...
Jae S. Lim, Hamid Nawab
openaire +1 more source
Speckle revisited: analysis of speckle noise in bar-code scanning systems
SPIE Proceedings, 2001-
Marom, E. +2 more
openaire +3 more sources
Reduction of speckle noise in multiwavelength contouring
Applied Optics, 2012We report on a method that can be used to improve the result of multiwavelength contouring in the case of objects with rough surface. It is based on the combined evaluation of multiple measurements with varying direction of illumination. While the individual measurements share the same systematics with respect to the shape of the investigated object ...
Claas, Falldorf +3 more
openaire +2 more sources