編寫的小波分解合成函數

function [S] = waves(signal,num,wavename) % load D105.mat % signal = data(:,1); % num = 10; % wavename = 'coif4'; % S = waves(signal,num,wavename) % figure % SS = sum(S.d(3:7,:)); % subplot(2,1,1) % plot(SS) % subplot(2,1,2) % plot(signal) %% 分解及合成 [d,a]= wavedec(signal,num,wavename); for i=1:numS.d(i,:) = wrcoef('d',d,a,wavename,i); end S.a=wrcoef('a',d,a,wavename,num); %% 畫圖 figure; subplot(num+2,1,1); plot(signal);ylabel('s');hold on; subplot(num+2,1,2); plot(S.a);ylabel(['a', num2str(num)]); for i=1:numsubplot(num+2,1,i+2);plot(S.d(i,:));ylabel(['d', num2str(i)]); end end

調用它的例子

clear;clc load D105.mat %是一個一維信號 signal = data(:,1); num = 10; wavename = 'coif4'; S = waves(signal,num,wavename); SS = sum(S.d(3:7,:)); figure; subplot(2,1,1) plot(SS) subplot(2,1,2) plot(signal)

smooth()%用于平滑曲線

wavemenu%打開小波工具箱

圖像去噪的實驗

clear all QQ = imread('QQ.bmp'); qq = double(QQ); Q = qq(:,:,1)+qq(:,:,2)+qq(:,:,3); Q=Q./3; load tire; X = Q; figure; subplot(2,2,1); image(X); colormap(map); title('原始圖像'); axis square; % h=20; h=180; x = X + h*randn(size(X)); subplot(2,2,2); image(x);colormap(map); title(['加入強度為',num2str(h),'的高斯噪聲后']); axis square; [c, s] = wavedec2(x,2,'sym4'); a1 = wrcoef2('a',c,s,'sym4',1); subplot(2,2,3);image(a1); title('第一次消噪后的圖像'); axis square; a2 = wrcoef2('a',c,s,'sym4',2); subplot(2,2,4); image(a2); axis square; title('第二次降噪后的圖像');

小波去噪

t = 0:pi/100:4*pi; s = sin(t+pi/4); subplot(5,1,1);plot(s); title('原始信號'); [c,l] = wavedec(s,3,'db1'); grid; ca3 = appcoef(c,l,'db1',3);%提取低頻 cd3 = detcoef(c,l,'db1',3);%提取第三層高頻系數 cd2 = detcoef(c,l,'db1',2);%提取第二層高頻系數 cd1 = detcoef(c,l,'db1',1);%提取第一層高頻系數 s1 = waverec(c,l,'db1');%重構小波信號 subplot(5,1,2);plot(s1);grid;title('重構信號');

小波降噪

總結

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