Results 241 to 250 of about 50,323 (284)

Speckle noise in displays

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, C. R. Christensen, J. S. Bennett, B. D. Guenther   +3 more
openaire   +1 more source

Laser vibrometer speckle-noise cancellation

Measurement Science and Technology, 1993
When 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, 2006
Speckle 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, 2002
The 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

Techniques For Speckle Noise Removal

Optical Engineering, 1981
In 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., Krešić-Jurić, Saša, Bergstein, L.   +2 more
openaire   +3 more sources

Reduction of speckle noise in multiwavelength contouring

Applied Optics, 2012
We 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, Silke, Huferath-von Luepke, Christoph, von Kopylow, Ralf B, Bergmann   +3 more
openaire   +2 more sources

Speckle grain noise in heterodyne techniques for holographic interferometry and speckle photogrammetry

Applied Optics, 1987
Heterodyne techniques greatly improved the accuracy in readout systems for holographic interferometry and dual plate speckle photogrammetry, since the order of interference fringes is read via phase measurements. The limiting accuracy has been traditionally associated with scintillation noise.
J S, Kim, M, Giglio, U, Perini, S, Musazzi   +3 more
openaire   +2 more sources

Noise reduction in speckle pattern interferometer

SPIE Proceedings, 2003
In speckle pattern interferometry the starting phase is distributed randomly. Furthermore the background intensity and the modulation also are structured stochastically. This leads to a significant amount of noise in the interferogram analysis. Low modulated speckles are more difficult to evaluate than high modulated ones.
J. Kauffmann, Markus Gahr, Hans J. Tiziani   +2 more
openaire   +1 more source

Elimination of Speckle Noise in Holograms with Redundancy

Applied Optics, 1968
Holograms made of diffusely reflecting or diffusely illuminated objects can be scratched, spotted with dirt, and even broken into pieces without serious loss of information. This remarkable property is due to the redundancy introduced by diffuse illumination which, in effect, spreads information all over the hologram.
H J, Gerritsen, W J, Hannan, E G, Ramberg   +2 more
openaire   +2 more sources