说明：  小波图像去噪程序。th=sigma*sqrt(2*log10(L*T)) 计算阈值 ch=c(1,num(4-i,1):num(4-i,3)+step(4-i)-1) 对各高频系数进行阈值处理 chl=length(ch) for j=1:chl if abs(ch(j))>=th ch(j)=sign(ch(j))*(abs(ch(j))-2*th/(1+exp(m*(ch(j)^2)))) 阈值处理函数 else
(Wavelet image denoising procedures. th = sigma* sqrt (2* log10 (L* T)) calculated threshold ch = c (1, num (4-i, 1): num (4-i, 3)+ step (4-i)-1) of the high-frequency coefficients thresholding chl = length (ch) for j = 1: chl if abs (ch (j))> = th ch (j) = sign (ch (j))* (abs (ch (j))-2* th/(1+ exp (m* (ch (j) ^ 2 )))) else threshold processing function)