共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
3.
4.
分形图像压缩编码是当今图像编码领域研究的热点之一,是一种具有独特优势且极有发展前途的数据压缩技术。本文从分形基本理论出发,对分形图像压缩编码思想、编码方法等进行了综述,并介绍了分形图像压缩编码的一些改进方法。最后,探讨了分形图像压缩编码的发展方向。 相似文献
5.
阐述了分形图像压缩的理论基础,了分形在视频图像空中的应用。分形图像压缩编码方法能够实现很高的压缩比,具有很高的实用价值。 相似文献
6.
7.
针对目前存在图像压缩率不高、全局搜索或遗传算法寻找最优分形图像压缩编码速度慢的不足,将基因表达式编程应用于分形图像压缩编码,提高求解分形图像压缩编码速度和压缩比.首先从理论上对二值图像压缩编码的求解过程和基因表达式编程在压缩编码中的作用机理进行分析;然后,研究分形图像压缩编码的基因和染色体的表示方法,适应度函数设计以及选择、变异、插串、基因变换、基因重组等基因遗传进化操作过程.提出基因表达式编程的分形图像压缩算法,求解分形图像压缩编码的最优解.实验结果表明,基因表达式编程应用于分形图像压缩编码,具有较强的全局寻优能力,搜索最优解的速度比遗传算法快约2倍,图像压缩率高. 相似文献
8.
小波分形混合图像压缩编码进展 总被引:2,自引:0,他引:2
介绍了分形、小波图像压缩编码进展情况,简要讨论了小波分形混合图像压缩的一般方法,并对国内外小波分形图像压缩的现状进行了详细的说明,探讨了静止图像压缩编码的发展方向。 相似文献
9.
10.
11.
On the relationship between fractal dimension and the performance of multi-resonant dipole antennas using Koch curves 总被引:1,自引:0,他引:1
Vinoy K.J. Abraham J.K. Varadan V.K. 《Antennas and Propagation, IEEE Transactions on》2003,51(9):2296-2303
This paper relates for the first time, multiple resonant frequencies of fractal element antennas using Koch curves to their fractal dimension. Dipole and monopole antennas based fractal Koch curves studied so far have generally been limited to certain standard configurations of the geometry. It is possible to generalize the geometry by changing its indentation angle, to vary its fractal similarity dimension. This variation results in self-similar geometry which can be generated by a recursive algorithm. Such a variation is found to have a direct influence on the input characteristics of dipole antennas. The primary resonant frequency, the input resistance at this resonance, and the ratio of first two resonant frequencies, have all been directly related to the fractal dimension. Curve-fit expressions can also be obtained for the performance of antennas at their primary resonance, in terms of fractal iteration and fractal dimension. The antenna characteristics have been studied using extensive numerical simulations and are experimentally verified. These findings underscore the significance of fractal dimension as an important mathematical property of fractals that can be used as a design parameter for antennas. The use of these ideas would not only reduce the computational intensity of optimization approaches for design of fractal shaped antennas, but also help antenna designers approach the problem systematically. Design formulation for antennas based on other fractal geometries can be similarly obtained after identifying suitable parameters of variation. This would therefore help analytical design of multiband and multifunctional antennas using fractal geometries. 相似文献
12.
This article proposes a novel design based on fractal geometries to miniaturize the antenna. The proposed geometry is inspired from a combination of two fractal geometries, Giuseppe Peano and Minkowski fractal geometry. The dielectric material used is Roggers TMM4 lossy, with a dielectric constant of εr = 4.5 the proposed geometry shows miniaturization by shifting the lowest resonant frequency towards the lower frequency side. The geometry is made by addition of the scaled version of base geometry at the vertices and reducing the total dimension so as to maintain the outer dimensions constant. The maximum achieved miniaturization in terms of % is 37.25%. The detailed study for different scaling ratios and different iterations has been performed and mentioned in the paper. 相似文献
13.
14.
S. V. Bulyarskii V. V. Svetukhin O. V. Agafonova A. G. Grishin P. A. Il’in 《Semiconductors》2001,35(8):861-863
The growth kinetics of lithium clusters in germanium is studied. Ham’s theory is generalized to describe the growth of fractal clusters. It is shown that the lithium clusters in germanium are characterized by a fractal geometry with a fractal dimension of 2.4. 相似文献
15.
将分形几何应用于天线设计可以产生具有多频段或小型化特征的分形天线。传统的多频段分形天线Sierpinski垫片天线由于是有限次迭代生成的,它存在截取效应低端谐振频率比值几乎是其几何相似性因子的两倍,从而限制了其实际应用。本文针对一种小型化的加载型Sierpinski垫片天线进行了有效的研究,证实了加载对降低天线高端谐振频率的有效性,同时分析了结构参数对其工作频段的影响并提出了增大天线张角的方式以进一步小型化天线。 相似文献
16.
17.
Fractal modeling and segmentation for the enhancement of microcalcifications in digital mammograms 总被引:3,自引:0,他引:3
The objective of this research is to model the mammographic parenchymal and ductal patterns and enhance the microcalcifications using a deterministic fractal approach. According to the theory of deterministic fractal geometry, images can be modeled by deterministic fractal objects which are attractors of sets of two-dimensional (2-D) affine transformations. The iterated functions systems and the collage theorem are the mathematical foundations of fractal image modeling. Here, a methodology based on fractal image modeling is developed to analyze and model breast background structures. The authors show that general mammographic parenchymal and ductal patterns can be well modeled by a set of parameters of affine transformations. Therefore, microcalcifications can be enhanced by taking the difference between the original image and the modeled image. The authors' results are compared with those of the partial wavelet reconstruction and morphological operation approaches. The results demonstrate that the fractal modeling method is an effective way to enhance microcalcifications. It may also be able to improve the detection and classification of microcalcifications in a computer-aided diagnosis system. 相似文献
18.
19.
《Electronics letters》2001,37(19):1150-1151
Fractal antenna engineering concepts have been successfully combined with genetic algorithms to develop a powerful design optimisation tool. The genetic optimisation approach developed can simultaneously optimise the geometry of a fractal antenna, locations of loads, component values of loads, and projected length of the fractal antenna. The results suggest that a 30 to 55% size reduction can be achieved by optimising the fractalisation of a given antenna. The knowledge gained from this study is directly applicable to the design of miniature multiband fractal antennas 相似文献