matlab 小波分析工具

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编写的小波分解合成函数

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:num    S.d(i,:) =  wrcoef('d',d,a,wavename,i);endS.a=wrcoef('a',d,a,wavename,num);%% 画图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:num    subplot(num+2,1,i+2);    plot(S.d(i,:));ylabel(['d', num2str(i)]);endend

调用它的例子

clear;clcload D105.mat%是一个一维信号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()%用于平滑曲线

wavemenu%打开小波工具箱

图像去噪的实验

clear allQQ = 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('原始图像');axis square;% h=20;h=180;x = X + h*randn(size(X));subplot(2,2,2);image(x);colormap(map);title(['加入强度为',num2str(h),'的高斯噪声后']);axis square;[c, s] = wavedec2(x,2,'sym4');a1 = wrcoef2('a',c,s,'sym4',1);subplot(2,2,3);image(a1);title('第一次消噪后的图像');axis square;a2 = wrcoef2('a',c,s,'sym4',2);subplot(2,2,4);image(a2);axis square;title('第二次降噪后的图像');

小波去噪

t = 0:pi/100:4*pi;s = sin(t+pi/4);subplot(5,1,1);plot(s);title('原始信号');[c,l] = wavedec(s,3,'db1');grid;ca3 = appcoef(c,l,'db1',3);%提取低频cd3 = detcoef(c,l,'db1',3);%提取第三层高频系数cd2 = detcoef(c,l,'db1',2);%提取第二层高频系数cd1 = detcoef(c,l,'db1',1);%提取第一层高频系数s1 = waverec(c,l,'db1');%重构小波信号subplot(5,1,2);plot(s1);grid;title('重构信号');

小波降噪

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