wavletdenoise.rar_db小波去噪_wavelet signal_信号还原_小波变换 db_小波变换去噪

% 本程序先生成一个“Blocks”信号，然后加上高斯白噪声，再用'db3'小波进行分解， % 以说明信号和噪声在各个尺度上的表现。 clear all; % 生成“Blocks”信号 % M = 1/1024; % N = 1/M; % t =0:M:1-1/1024; % TPoint = [0.1,0.13,0.15,0.23,0.25,0.40,0.44,0.65,0.76,0.78,0.81]; % h = [4,-5,3,-4,5,-4.2,2.1,4.3,-3.1,2.1,-4.2]; % [aaa,TSize] = size(TPoint); % FBlock = zeros(N,1); % for j = 1:N % for i = 1:TSize % if (t(j) - TPoint(i))> 0 % sgnt = 1; % elseif (t(j) - TPoint(i))< 0 % sgnt = -1; % else % sgnt =0; % end % FBlock(j) = FBlock(j) +h(i)*(1+sgnt)/2; % end % end %sig=FBlock'; FBlock = imread('lena.bmp') % subplot(121) figure(1) imshow(FBlock) title(' 原信号'); % grid on; % 加上白噪声 % sigma=0.1; % SNR=20.0; % sig=awgn(FBlock,SNR,sigma);%原信号功率0.1加入白噪声 sig=imnoise(FBlock,'gaussian',0,0.01) % subplot(122) figure(2) imshow(sig) title(' 带噪信号'); grid on; % 小波分解 [c,l]=wavedec(sig,2,'db3'); ca2=appcoef(c,l,'db3',2);%提取低频系数 cd2=detcoef(c,l,2);%高频系数 %ans=size(cd2); cd1=detcoef(c,l,1); % subplot(322) % plot(cd1) % subplot(324) % plot(cd2) % subplot(326) % plot(ca2) %只使用低频系数重构 dl=length(cd2)+length(cd1); c1=[ca2;zeros(dl,1)];%为什么不能直接ca2在waverec中使用？？ y=waverec(c1,l,'db3'); %========================= %使用低频系数与一级分解高频系数重构 % dl=length(cd2); % c1=[ca2;zeros(dl,1);cd1]; % y=waverec(c1,l,'db3'); %========================= %使用低频系数与二级分解高频系数重构 %========================= % dl=length(cd1); % c1=[ca2;cd2;zeros(dl,1)]; % y=waverec(c1,l,'db3'); %========================= %========================= % y=waverec(c,l,'db3'); %========================= % subplot(325) % plot(y) figure(3) imshow(FBlock)