Crustal movement modeling and analysis is one of the major tasks in the earth system science. In this paper, a distributed system for simulating the crustal movement was developed. The crustal movement simulation syst...
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Iterative reconstruction techniques are safe approaches for computed tomography (CT). However, the long processing time of them prevent their adoption in clinical CT machines. Recently, with the growing increase in co...
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ISBN:
(纸本)9780889868687
Iterative reconstruction techniques are safe approaches for computed tomography (CT). However, the long processing time of them prevent their adoption in clinical CT machines. Recently, with the growing increase in computational power due to multiple cores on a chip, iterative techniques are no longer deemed unsolvable. In this paper, we investigate one category of iterative techniques which stem from algebraic reconstruction technique, including ART (algebraic reconstruction technique), SIRT (simultaneous iterative reconstruction technique), SART (simultaneous algebraic reconstruction technique), and ordered subset version of SART (OS-SART). We exploit the parallelism in OS-SART and its feasibility to parallelization on homogenous shared memory multicore architectures. OSSART is memory bound due to the frequent access to a large weighting factor matrix. Therefore, to reduce memory latency in OS-SART, we parallelize OS-SART algorithm by incorporating rotation-based projector and backprojector which enables the computation of weighting factors at runtime on a need basis. The results show that our parallel algorithm is scalable on homogeneous multicore architecture in terms of both core number and problemsize. For 8 cores, the speedup increases from 6.77 for image size of 128×128 to 7.02 for image size of 512×512. For 16 cores, the speedup increases from 12.29 for image size 128×128 to 13.18 for image size 512×512.
In a digital optical imaging system, image resolution is constrained by several factors, including focus plane array pitch and optics. Super-resolution approaches aim at overcoming some of these limits by incorporatin...
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ISBN:
(纸本)9780982443811
In a digital optical imaging system, image resolution is constrained by several factors, including focus plane array pitch and optics. Super-resolution approaches aim at overcoming some of these limits by incorporating additional information of the object and/or combining several pictures of the same object, taken with some displacements between each other. This paper considers the second class of methods. The obtainable resolution improvement in this case has an upper limit, determined by the signal-to-noise ratio of the image taken. Moreover, some fourier spectrum frequencies below this limit are unrestorable. Here an approach is introduced to overcome this by active control of the camera movements. An experiment, verifying the approach is presented.
Digitization of real objects into 3D models is a rapidly expanding field, with ever increasing range of applications. The most interesting area of its application is in the creation of realistic 3D scenes, i.e. virtua...
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This paper addresses the optimization of parallel simulators for large-scale parallel systems and applications. Such simulators are often based on parallel discrete event simulation with conservative or optimistic pro...
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A method is proposed for 3-D reconstruction of coronary from a limited number of projections in rotational angiography. A Bayesian maximum a posteriori (MAP) estimation is applied with a Poisson distributed projection...
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ISBN:
(纸本)9781424441242
A method is proposed for 3-D reconstruction of coronary from a limited number of projections in rotational angiography. A Bayesian maximum a posteriori (MAP) estimation is applied with a Poisson distributed projection to reconstruct the 3D coronary tree at a given instant of the cardiac cycle. Several regularizers are investigated L0-norm, L1 and L2-norm in order to take into account the sparsity of the data. Evaluations are reported on simulated data obtained from a 3D dynamic sequence acquired on a 64-slice GE LightSpeed CT scan. A performance study is conducted to evaluate the quality of the reconstruction of the structures.
Secret image sharing is a method to transmit and store an image safely. The security of secret image sharing is based on the fact that the values are operated in the finite field and the number of pixels is high enoug...
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Secret image sharing is a method to transmit and store an image safely. The security of secret image sharing is based on the fact that the values are operated in the finite field and the number of pixels is high enough to ensure security. However, the time complexity to encode and decode a secret image is not acceptable in real-time application. There are some papers discussing how to upgrade the efficiency of encoding phase while few papers exploring how to decrease the decoding phase time. This paper proposes a method to achieve to speed up decoding phase by parallelprocessing.
The paper presents the application of different filtering algorithms to simplify the search for suspicious objects on the X-ray image obtained by SRC "Sibscan". The basic idea of x-ray image filtering is an ...
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ISBN:
(纸本)9780889868410
The paper presents the application of different filtering algorithms to simplify the search for suspicious objects on the X-ray image obtained by SRC "Sibscan". The basic idea of x-ray image filtering is an image contrast enhancement with minimal loss of information. We have proposed a new method of obtaining image luminance differences, allowing to identify 12 directions in the 35 * O (N) operations on the image. We had shown that the combination of the logarithm of the image and the image gradients can improve the visual quality of the latter. A study was conducted with existing methods of histogram equalization, in that study the method of adaptive histogram equalization had shown the best results. Combination of the adaptive equalized image and the image gradient corrects deficiencies of the equalization. Filtering algorithms were implemented in a software system, written on programming language C+ +. imageprocessing takes 3 seconds on a standard PC with image size of 1000 by 1024 pixels, and can be accelerated on parallel computation using multiple cores in accordance to the technology OpenMP.
We introduce a novel method for the consolidation of unorganized point clouds with noise, outliers, non-uniformities as well as sharp features. This method is feature preserving, in the sense that given an initial est...
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Interactions between humans or humanoids and their environment through tasks like grasping or manipulation typically require accurate depth information. The human vision system integrates various monocular and binocul...
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ISBN:
(纸本)9781424466757
Interactions between humans or humanoids and their environment through tasks like grasping or manipulation typically require accurate depth information. The human vision system integrates various monocular and binocular depth estimation mechanisms in order to achieve robust and reliable depth perception. Such an integrated approach can be applied to humanoid depth perception. Integration requires a knowledge of the characteristics of the methods being combined. Three different methods incorporating active vision (stereo disparity, vergence and familiar size) were statistically examined and combinations of these methods based on this statistical examination were investigated. We found evidence that active vision provides better depth estimations than the standard static-parallel stereo methods examined within interaction range and therefore is better suited for tasks like reaching, grasping and manipulation. We also demonstrate that a combination of methods have the potential to increase the accuracy of estimations.
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