摘要：建立了一类二阶中立型差分方程渐近性的两个准则,推广了文献[1](JIN Guang-zhi,HOU Cheng-min,HE Yan-sheng.On the asymptotic behavior of certain second order difference equations.延边大学学报(自然科学版),2005,31(4):247-248)的结果.
摘要：分形压缩技术存在很多优点,但其还存在编码时间过长的缺点.理论已经证明IFS不会改变图像块的熵值.本文提出了一种基于改进熵值的分形压缩算法:一是采用改进的熵值进行判断,降低了算法的复杂度,二是通过合并定义域池使编码时间减少.实验结果表明,采用该方法时的编码时间和PSNR较其他算法有明显提高,压缩比也有所提高.%Despite the advances made, the long computing time in the encoding phase still remain the main drawback of the fractal compression technique. It is known that the IFS can not change the image blocks' entropy values. However, a novel fractal compression approach based on reformed entropy is presented. The reformed entropy reduced the complex of the algorithm, on the other hand, the matched blocks are reduced by combining the pools of the domains, which decreases the encoding time. The simulation results illuminate that the new method has high efficiency, and it can improve the PSNR and the computing time compared with other fast algorithms, the compression ratio is also increased.
