Results 211 to 220 of about 230,662 (251)

Effective signal-to-noise ratio improvement by parametric image amplification

Optics Letters, 2006
We show experimentally that parametric optical preamplification greatly improves the signal-to-noise ratio of an image if the detector has a poor quantum efficiency and/or a great level of readout noise. Results are fully consistent with the theory of quantum-noise-limited amplification.
Devaux, F., Blanchet, J.L., Lantz, E.
openaire   +4 more sources

An unbiased signal‐to‐noise ratio measure for magnetic resonance images

Medical Physics, 1993
Estimating the true signal‐to‐noise ratio (SNR) of magnetic resonance (MR) images with low signal is confounded by the magnitude presentation of the data. This paper suggests a simple solution to this problem. A common method of measuring SNR compares the mean signal to the standard deviation of the noise.
Michael Smith, G. McGibney
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Improvement of lesion detection by echographic image processing: signal-to-noise-ratio imaging.

Ultrasonic imaging (Print), 1991
J. Verhoeven, J. Thijssen, A. Theeuwes
semanticscholar   +2 more sources

Signal-to-Noise and Contrast Ratio Enhancements by Quasi-Monochromatic Imaging

IEEE Transactions on Instrumentation and Measurement, 2009
Computed tomography (CT) exams provide orders of magnitude higher radiation than a single-view X-ray. The chance of getting cancer from X-ray radiation has been increasing by 1.5-2% at every CT exam. Therefore, decreasing the dose per CT exam is a major goal. The aims of this study were to find out how one can improve the signal-to-noise ratio (S/N) or
openaire   +3 more sources

Signal to Noise Ratio in Stem and Low-Loss Images

Proceedings, annual meeting, Electron Microscopy Society of America, 1980
The number of pixels or resolution elements in STEM images has frequently been relatively low (< 105) and in many images only a few gray levels can be distinguished. This is surprising considering the high brightness of the electron sources used in most cases,
openaire   +2 more sources

Imaging signal-to-noise ratio of synthetic aperture ladar

SPIE Proceedings, 2015
On the basis of the Poisson photocurrent statistics in the photon-limited heterodyne detection, in this paper, the signal-to-noise ratios in the receiver in the time domain and on the focused 1-D image and 2-D image in the space domain are derived for both the down-looking and side-looking synthetic aperture imaging ladars using PIN or APD photodiodes.
openaire   +2 more sources

Signal-to-noise ratios in NMR imaging

Magnetic Resonance Imaging, 1982
Kevin F. King, Paul R. Moran
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Image-Adaptive Watermarking Using the Improved Signal to Noise Ratio

2006 International Conference on Computational Intelligence and Security, 2006
This paper presents a new perceptual quality metric (PQM), the improved signal to noise ratio (iSNR). The improvement is done in the following two aspects: 1) the SNR manifests much better performance in an image block of small size than in a whole image; 2) the average luminance and gradient information are added into the SNR. Next, a locally adaptive
openaire   +3 more sources

Contrast and signal-to-noise ratio in long-distance starlight imaging

Applied Optics, 1996
A small telescope on an airplane or in low Earth orbit can, in principle, resolve ground objects under starlight with useful resolution. For an ~50-cm aperture and ~100-s exposure, one can obtain a resolution of tens of centimeters from an aircraft and a few meters from orbit.
openaire   +3 more sources

Molecular imaging in oncology: Current impact and future directions

Ca-A Cancer Journal for Clinicians, 2022
Martin G Pomper, Steven P Rowe
exaly