阈值分割技术.doc

阈值分割技术毕业设计中文摘要摘要小波分析理论是一种新兴的信号处理理论, 它在时间上和频率上都有很好的局部性,这使得小波分析非常适合于时- 频分析,借助时- 频局部分析特性, 小波分析理论已经成为信号去噪中的一种重要的工具。利用小波方法去噪, 是小波分析应用于实际的重要方面。小波去噪的关键是如何选择阈值和如何利用阈值来处理小波系数, 通过对小波阈值化去噪的原理介绍, 运用 MATLAB 中的小波工具箱, 对一个含噪信号进行阈值去噪, 实例验证理论的实际效果, 证实了理论的可靠性。本文简述了几种小波去噪方法, 其中的阈值去噪的方法是一种实现简单、效果较好的小波去噪方法。小波分析的出现是信号处理领域的一次重大革命, 然后由于传统的硬阈值函数滤波存在使信号会产生振荡不具有同原始信号一样的光滑性, 而软阈值函数存在丢失信号的某些特征。根据需要构造了一个新的阈值函数, 从而克服了软、硬阈值函数的缺点, 由仿真模拟可以看出效果良好。本文根据已有的阈值处理函数的优缺点, 提出了一种新的阈值处理函数, 用于图像的小波阈值去噪. 实验表明, 该方法比传统的硬阈值函数与软阈值函数具有更好的去噪效果。关键词:小波阈值去噪,阈值函数, 小波分析, 滤波 I毕业设计外文摘要 Title Abstract The wavelet analysis theory isa new signal processing theory. It has a very good topicality in time and frequency, which makes the wavelet analysis very suitable for the time - frequency analysis. With the time - frequency?s local analysis characteristics, the wavelet analysis theory has e an important tool in the signal de-noising. Using wavelet methods in de-noising, is an important aspect in the application of wavelet analysis. The key of wavelet de-noising is how to choose a threshold and how to use thresholds to deal with wavelet coefficients. It confirms the reliability of the theory through the wavelet threshold de-noising principle, the use of the wavelet toolbox in MATLAB, carrying on threshold de-noising for a signal with noise and actual results of the example confirmation theory. This paper has summarized several methods about the wavelet de-noising, in which the threshold de-noising isa simple, effective method of wavelet de- emergence of wavelet analysis isa signal processing field ofa major revolution, then the traditional hard threshold function filter the signal will be generated oscillations do not have the same original signal the same smoothness, and the soft threshold function has lost signal characteristics. According to the need to construct a new threshold function, thereby ing the disadvantages of soft, hard threshold function, the effect can be seen well by this paper, on the bas