swt1d_recon.m

编程实现基于小波变换尺度相关性去噪算法

function s = swt1d_recon(a,d,n,h,g)
%UNTITLED1 Summary of this function goes here
%  Detailed explanation goes here

% Preserve initial size.
l = length(a(:,1));
max_n = size(a,2);
pow = 2^n;        

% 设置 DWT_Mode 为 'per',即周期延拓
modeDWT = 'per';

% 一系列参数的初始化操作.
si = 1;
evenoddVal = 1;  %用于控制滤波器的上/下抽样
s(:,si) = a(:,max_n); %初始化重构矩阵

%初始化滤波器
for i=1:max_n-1
    g = dyadup(g,evenoddVal);
    h = dyadup(h,evenoddVal);
end

for k = max_n:-1:max_n-n+1   %开始逐级计算重构
%     shift=ceil(2^(k-1)-0.5); %shift用于抵消 平移的误差
    if(k==1)
        shift = 0;
    else
        shift = -1;
    end

    % 延拓
    lfh = length(h);
    lfg = length(g);
%     size(s(:,si))
    aa = wextend('1D',modeDWT,s(:,si),round(lfh/2));
    dd  = wextend('1D',modeDWT,d(:,k),round(lfg/2));
    
    % 重构.逼近矩阵
%     size(aa)
    aa = wkeep(wconv('1D',aa,h),l,floor(lfh-shift)); % a*h
      
    % 重构. 水平细节信息矩阵d1 
    dd= wkeep(wconv('1D',dd,g),l,floor(lfg-shift));  % d1*(g,l)
    aa = aa + dd;    
    aa = aa./2;
    
    si = si+1;
    s(:,si) = aa;

    % 对滤波器进行下抽样
    g = dyaddown(g,1-evenoddVal);
    h = dyaddown(h,1-evenoddVal);
end