The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Gonzalo Pajares - One of the best experts on this subject based on the ideXlab platform.
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noniterative interpolation based super resolution minimizing aliasing in the Reconstructed Image
IEEE Transactions on Image Processing, 2008Co-Authors: Alfonso Sanchezbeato, Gonzalo PajaresAbstract:Super-resolution (SR) techniques produce a high-resolution Image from a set of low-resolution undersampled Images. In this paper, we propose a new method for super-resolution that uses sampling theory concepts to derive a noniterative SR algorithm. We first raise the issue of the validity of the data model usually assumed in SR, pointing out that it imposes a band-limited Reconstructed Image plus a certain type of noise. We propose a sampling theory framework with a prefiltering step that allows us to work with more general data models and also a specific new method for SR that uses Delaunay triangulation and B-splines to build the super-resolved Image. The proposed method is noniterative and well posed. We prove its effectiveness against traditional iterative and noniterative SR methods on synthetic and real data. Additionally, we also prove that we can first solve the interpolation problem and then make the deblurring not only when the motion is translational but also when there are rotations and shifts and the imaging system point spread function (PSF) is rotationally symmetric.
Xiao-ou Cai - One of the best experts on this subject based on the ideXlab platform.
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Study on the reduction of speckle noise in the Reconstructed Image of digital hologram
Optik, 2014Co-Authors: Xiao-ou CaiAbstract:Abstract As one of the most important 3-D display technique, reduction of speckle noise in the Reconstructed Image of digital holography should be grounded on the digital hologram itself. Based on the whole process of the recording and reconstruction of digital holography, the optical distributions of recorded object and Reconstructed Image of digital holography have been studied. It has been proposed that the root formation cause of speckle noise in its Reconstructed Image is the speckle noise formed on the recorded object surface when illuminated by coherent light because of its optical roughness. A novel approach has been presented to reduce speckle noise in digital holography by changing the interference structure of hologram itself. First, by reducing the speckle noise in the Reconstructed Image, the distribution of ideal reconstruction light with reduced speckle noise is acquired. Then in turn, taking the ideal reconstruction light with reduced speckle noise as ideal object light, a new hologram can be rebuilt, which can reconstruct the ideal object light. The experimental results are given to confirm the proposed method. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the Reconstructed Image of digital holography.
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Reduction of speckle noise in the Reconstructed Image of digital holography
Optik, 2010Co-Authors: Xiao-ou CaiAbstract:Based on the whole process of recording and reconstruction of digital holography, we study the formation causes of speckle noise in the Reconstructed Image and its characteristics. And we reach the conclusions that the little hologram aperture diffraction aggravates the speckle noise and the speckle noise in the Reconstructed Image is a kind of multiplicative noise. Serving as the basis of these features, we propose the reduction technique for speckle noise. Firstly, we set an appropriate aperture function matching the recording parameter and an aperture size of hologram and deconvolve the Reconstructed Image of the hologram with it. Secondly, we converted the multiplicative noise into additive noise by means of homomorphic transform and realize the separation of signal and noise. Thirdly, we applied the Wiener filtering to reduce the additive noise. Finally, we carried out the inverse transformation. The proposed reduction technique is illustrated with experimental results. Therefore, the paper offers a brand-new thought and practical way of reducing the speckle noise in the Reconstructed Image of digital holography.
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The influence of hologram aperture on speckle noise in the Reconstructed Image of digital holography and its reduction
Optics Communications, 2008Co-Authors: Xiao-ou Cai, Hui WangAbstract:Based on the whole process of the recording and reconstruction of digital holography, we study the formation cause of speckle noise in its Reconstructed Image and acquire the conclusion that the small size of hologram aperture diffraction aggravates the speckle noise of Reconstructed Image and the speckle noise has been one of primary noise sources in the reconstruction process. In order to reduce the speckle noise resulting from little hologram aperture diffraction, we set an appropriate aperture function matching the recording parameter and aperture size of hologram and deconvolve the Reconstructed Image with it. The validity has been proved in theory and experiment. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the Reconstructed Image of digital holography.
Alfonso Sanchezbeato - One of the best experts on this subject based on the ideXlab platform.
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noniterative interpolation based super resolution minimizing aliasing in the Reconstructed Image
IEEE Transactions on Image Processing, 2008Co-Authors: Alfonso Sanchezbeato, Gonzalo PajaresAbstract:Super-resolution (SR) techniques produce a high-resolution Image from a set of low-resolution undersampled Images. In this paper, we propose a new method for super-resolution that uses sampling theory concepts to derive a noniterative SR algorithm. We first raise the issue of the validity of the data model usually assumed in SR, pointing out that it imposes a band-limited Reconstructed Image plus a certain type of noise. We propose a sampling theory framework with a prefiltering step that allows us to work with more general data models and also a specific new method for SR that uses Delaunay triangulation and B-splines to build the super-resolved Image. The proposed method is noniterative and well posed. We prove its effectiveness against traditional iterative and noniterative SR methods on synthetic and real data. Additionally, we also prove that we can first solve the interpolation problem and then make the deblurring not only when the motion is translational but also when there are rotations and shifts and the imaging system point spread function (PSF) is rotationally symmetric.
K. Knesaurek - One of the best experts on this subject based on the ideXlab platform.
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Investigation Of Reconstructed Image Quality In Spect
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society Volume 13: 1991, 1Co-Authors: K. KnesaurekAbstract:Several fundamental variables, which can significantly effect the quality of Reconstructed Images in single photon emission computed tomography (SPECT) obtained remain. These are attenuation, spatial resolution, scatter, and noise as well as linear and angular sampling. At present, serious controversy is the choice of angular data sampling. The question is whether angular data sampling around complete 360' rotation is necessary or a limited 180' arc would be sufficient. Data obtained from point source in addition to a three-dimensional analytical, non-stationary simulation study are used. The results of these studies have confirmed that the 180' Reconstructed Images suffer more severely than 360' Images from variable geometric distortion.
Norimasa Nohara - One of the best experts on this subject based on the ideXlab platform.
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the local noise property in positron volume imaging and optimal conditions for the signal to noise ratio of the 3d Reconstructed Image
Physics in Medicine and Biology, 1997Co-Authors: Hideo Murayama, Norimasa NoharaAbstract:The local noise property of a 3D PET Reconstructed Image is investigated for a uniform-activity sphere distributed in a constantly attenuating spherical object. The positional dependence of the statistical noise is approximately derived and calculated for some special cases. It is suggested that a larger diameter of the activity sphere causes noise amplification, and the noise property for the large attenuating sphere is close to that for a non-attenuating object with the same total number of measuring counts. By considering noise propagation of two spherical activity distributions, we suggest that the signal-to-noise ratio of the Image depends on a set of projection directions and the sizes and intensities of the activity distributions. In a simple case, we derive an optimal value of the maximum acceptance angle for the projection directions to improve the signal-to-noise ratio of the Image.
