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21.
Multispectral Image Compression for Improvement of Colorimetric and Spectral Reproducibility by Nonlinear Spectral Transform 总被引:1,自引:0,他引:1
Shanshan Yu Yuri Murakami Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2006,13(5):346-356
The article proposes a multispectral image compression scheme using nonlinear spectral transform for better colorimetric and
spectral reproducibility. In the method, we show the reduction of colorimetric error under a defined viewing illuminant and
also that spectral accuracy can be improved simultaneously using a nonlinear spectral transform called Labplus, which takes
into account the nonlinearity of human color vision. Moreover, we show that the addition of diagonal matrices to Labplus can
further preserve the spectral accuracy and has a generalized effect of improving the colorimetric accuracy under other viewing
illuminants than the defined one. Finally, we discuss the usage of the first-order Markov model to form the analysis vectors
for the higher order channels in Labplus to reduce the computational complexity. We implement a multispectral image compression
system that integrates Labplus with JPEG2000 for high colorimetric and spectral reproducibility. Experimental results for
a 16-band multispectral image show the effectiveness of the proposed scheme. 相似文献
22.
Using scattered radiation as useful information to improve radioisotope image quality is a topic attracting many researchers. Some reports showed that incorporating scattered components offers a possibility to improve image quality. The general method is modeling scatter in multiple energy windows and incorporating that information into the reconstruction process. However, what the performance will be and how noise will behave when using scattered radiation in reconstruction are not yet well answered. In this paper, we investigate a method of modeling scatter in multiple energy windows in cases of a few projection views. The system performance is analyzed using singular value decomposition and resolution kernels. For noise behavior investigation, reconstructions are accomplished by estimating the variance of reconstructed voxel values and the effectiveness of using scatter is evaluated by resolution kernel analysis. The results show there are improvements in normalized mean-square error of the images and the resolution kernels. When photon counts fall below about one million, it is still effective to use scatter for some cases of a few projections 相似文献
23.
In image reconstruction for X-ray computed tomography, images reconstructed by filtered backprojection (FBP) include systematic errors because the FBP method does not take into account some of the properties of the actual imaging system such as the divergence of X-ray beam. One solution to this problem is to use algebraic reconstruction methods, such as generalized analytic reconstruction from discrete samples and natural pixel decomposition. However, in the process of reconstruction using these methods, it is necessary to solve the linear algebraic equations which have a large coefficient matrix. In this paper, we propose a method to accelerate the iteration solving these equations by preconditioning the coefficient matrix using a polynomial function. The results of the computer simulations show the effectiveness of the proposed method. 相似文献
24.
Yoshihiro Edo Shinnosuke Obi Sigeaki Masuda 《International Journal of Heat and Fluid Flow》2000,21(6)
The influence of Coriolis force on heat transfer in a rotating transitional boundary layer has been experimentally investigated. The experiments have been conducted for local Görtler numbers up to 150. Heat transfer measurements have been performed for a flat plate with nearly uniform heat flux applied to the surface, where the temperature was measured by the thermochromic liquid crystal method. The results indicate that heat transfer is enhanced when Coriolis force acts towards the wall, i.e., on the pressure surface. The velocity measurements under equivalent conditions show that Coriolis instability induces counter-rotating longitudinal vortices which augment the lateral transport of the fluid on the pressure surface. On the other hand, the heat transfer on the suction surface remains at the same level as compared to the case without system rotation. As a consequence, the heat transfer coefficient on the pressure surface is 1.8 times higher than that measured on the suction surface when averaged over the measured surface. 相似文献
25.
Opto-Electronic Block-Cipher Based on Iteration of the 2-D Toggle Cellular Automata: Algorithm 总被引:2,自引:0,他引:2
Maria Madjarova Mitsugu Kakuta Takashi Obi Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》1999,6(2):110-117
Parallel architectures and algorithms may offer a solution to the system bottleneck arising from the need to encrypt a very large amount of data without compromising security. In this respect the use of cellular automata with their parallel, simple, regular and modular structure is very promising. We extend the blockcipher algorithm, based on the iterations of so called “toggle” cellular automata rules to two dimensions.The advantages are higher complexity of the crypt-analytical attacks and substantial increase in the speed of the algorithm. Due to its massive parallelism and interconnectivity, the algorithm is very suitable for opto-electronic implementation. 相似文献
26.
We have generated thep-cyanobenzyl radical in supersonic free expansion, and measured the vibrationally and rotationally resolved laser induced fluorescence (LIF) excitation spectra and the LIF dispersed spectra from the single vibronic levels (SVL) in the green-blue region. The lowest energy band at 20 738 cm−1with the strongest intensity in the excitation spectrum has been assigned to the 000band of the visible spectrum, on the basis of the vibronic structures in the SVL dispersed spectra. Based on the band type of the 000band,a-type, determined from the rotationally resolved LIF excitation spectrum, we have definitely assigned the visible band to theD122B1–D012B1electronic transition. We have found, on the grounds of the vibrational analysis of the dispersed spectra, that the vibronic structure of the 22B1–12B1electronic transition of the benzyl type is characterized by totally symmetric fundamental modes, 1, 8a, and 9a. 相似文献
27.
C. Uma Maheswari K. Obi Reddy E. Muzenda M. Shukla A. Varada Rajulu 《International Journal of Polymer Analysis and Characterization》2013,18(6):439-450
In this work, composite samples were prepared using Borassus fibers and a high-density polyethylene matrix. Alternatively, a chemically modified matrix (maleic anhydride grafted HDPE) was also used to improve fiber-matrix compatibility. The effect of fiber loading on the mechanical properties was investigated. Borassus fiber/modified HDPE composites exhibited improved mechanical performance as compared to pure HDPE composites. SEM studies on the fractured specimens of unmodified HDPE fiber composites reveal the poor fiber-matrix interaction, whereas the interaction is strong with enhanced mechanical properties for modified HDPE fiber composites. This is due to an improvement of the chemical bonding between the modified HDPE matrix and the Borassus fiber as also supported by Fourier transform infrared spectroscopy results. Thermal stability was also found to be enhanced slightly for modified HDPE composites. 相似文献
28.
The SRVL fluorescenee lifetimes and fluorescence excitation spectra of the HNO ã1A″ -X1AA′ transition were measured in a supersonic free jet. The cooling of a rotational temperature in the jet made it possible to clear up the parity-selected perturbations in the asymmetric rotor under higher resolution condition. The fluorescence lifetimes of strongly perturbed levels, i.e. HNO ã1A″ 011 rovibronic levels were observed with dual exponential decay profiles, while non-perturbed levels exhibited single ones. The SRVL fluorescence lifetimes and fluorescence excitation spectra of DNO ã1″ -X1A′ were measured under the same condition as HNO. The rotationll analysis of the DNO ã1A″ 011 rovibronic levels was first carried out in the jet. 相似文献
29.
Mitsuyasu Yatsuzuka Kikoh Satoh Sadao Nobuhara Kiyoshi Yatsui Masahiro Yokoyama 《Physics letters. A》1983,95(6):293-296
Parametric excitation of the drift wave is observed by an ion beam modulated near the lower-hybrid frequency. An rf field parallel to the magnetic field is found to play an important role in the excitation of the instability. Substantial increase of the ion and electron temperatures is observed. 相似文献
30.
An organocatalyst-mediated, asymmetric Mannich reaction in the presence of water without using organic solvents has been developed. A highly reactive siloxytetrazole hybrid catalyst has been developed for the reaction of dimethoxyacetaldehyde, while the sodium salt of siloxyproline is an effective catalyst of alpha-imino glyoxylate. Excellent enantioselectivity can be realized, and the usage of organic solvents can be reduced compared to the conventional reactions in organic solvents. 相似文献