小波去噪中软硬阈值的一种改良折衷法

在小波域中分析了传统软阈值法和硬阈值法的特点,并在标准软硬阈值折衷法的基础上,提出了一种软硬阈值改良折衷法.与标准软硬阈值折衷法相比,其阈值函数具有更加灵活多变的形式,便于进行各种数学处理;与传统软阈值法和硬阈值法相比,它克服了硬阈值函数不连续的缺点,减小了软阈值函数中的估计小波系数与分解小波系数之间存在的恒定偏差.仿真实验结果表明,该改良方法的去噪性能优于传统软阈值法、硬阈值法、标准软硬阈值折衷法及一些现有的新阈值函数法.

An improved compromise for soft/hard thresholds in wavelet denoising

The characteristics of two traditional wavelet comp romise methods, referred to as the soft2thresholding method and the hard2thresholding method, were analyzed in the wavelet domain. A new comp romise thresholding method that imp roves performance is p resented, based on the standard comp romise thresholdmethod, yetmore flex2 ible and easier to treatmathematically. Compared with traditionalwavelet comp romise methods, the new app roach avoids the discontinuity of the hard2threshold method and also decreases the fixed bias between the estimated wave2 let coefficients and the decomposed wavelet coefficients of the soft2threshold method. Simulation results show that the imp roved method is better at denoising than the soft2threshold method, the hard2threshold method, the standard comp romised threshold method, aswell as other threshold function methods.