基于opencv的小波变换代码和图像结果

时间：2024-03-06 22:39:07
  1 #include "stdafx.h"
  2 #include "WaveTransform.h"
  3 #include <math.h>
  4 #include <imgproc/imgproc.hpp>

  
  5 Mat WaveTransform::WDT(const Mat &_src,const string _wname,const int _level)
  6 {
  7     Mat src=Mat_<float>(_src);
  8     Mat dst=Mat::zeros(src.rows,src.cols,src.type());
  9     int N=src.rows;
 10     int D=src.cols;
 11     //高通低通滤波器
 12     Mat lowFilter;
 13     Mat highFilter;
 14     wavelet(_wname,lowFilter,highFilter);
 15     //小波变换
 16     int t=1;
 17     int row=N;
 18     int col=D;
 19     while (t<=_level)
 20     {
 21         //先进行 行小波变换
 22         for (int i=0;i<row;i++)
 23         {
 24             //取出src中要处理的数据的一行
 25             Mat oneRow=Mat::zeros(1,col,src.type());
 26             for (int j=0;j<col;j++)
 27             {
 28                 oneRow.at<float>(0,j)=src.at<float>(i,j);
 29             }
 30             oneRow=waveletDecompose(oneRow,lowFilter,highFilter);
 31             for (int j=0;j<col;j++)
 32             {
 33                 dst.at<float>(i,j)=oneRow.at<float>(0,j);
 34             }
 35         }
 36         char s[10];
 37         itoa(t,s,10);
 38         imshow(s,dst);
 39         waitKey();
 40 #if 0
 41     //    normalize(dst,dst,0,255,NORM_MINMAX);
 42         IplImage dstImg1=IplImage(dst);
 43         cvSaveImage("dst1.jpg",&dstImg1);
 44 #endif
 45 
 46         //小波列变换
 47         for (int j=0;j<col;j++)
 48         {
 49             Mat oneCol=Mat::zeros(row,1,src.type());
 50             for (int i=0;i<row;i++)
 51             {
 52                 oneCol.at<float>(i,0)=dst.at<float>(i,j);//dst,not src
 53             }
 54             oneCol=(waveletDecompose(oneCol.t(),lowFilter,highFilter)).t();
 55             for (int i=0;i<row;i++)
 56             {
 57                 dst.at<float>(i,j)=oneCol.at<float>(i,0);
 58             }
 59         }
 60 #if 0
 61         //    normalize(dst,dst,0,255,NORM_MINMAX);
 62         IplImage dstImg2=IplImage(dst);
 63         cvSaveImage("dst2.jpg",&dstImg2);
 64 #endif
 65         //更新 
 66         row/=2;
 67         col/=2;
 68         t++;
 69         src=dst;
 70         
 71     }
 72     return dst;
 73 }
 74 

 75 //生成不同类型的小波
 76 void WaveTransform::wavelet( const string _wname, Mat &_lowFilter, Mat &_highFilter )
 77 {
 78     
 79     if (_wname=="haar" || _wname=="db1")
 80     {
 81         int N=2;
 82         _lowFilter=Mat::zeros(1,N,CV_32F);
 83         _highFilter=Mat::zeros(1,N,CV_32F);
 84 
 85         _lowFilter.at<float>(0,0)=1/sqrtf(N);
 86         _lowFilter.at<float>(0,1)=1/sqrtf(N);
 87 
 88         _highFilter.at<float>(0,0)=-1/sqrtf(N);
 89         _highFilter.at<float>(0,1)=1/sqrtf(N);
 90     }
 91     if (_wname=="sym2")
 92     {
 93         int N=4;
 94         float h[]={-0.483, 0.836, -0.224, -0.129};
 95         float l[]={-0.129, 0.224,    0.837, 0.483};
 96         
 97         _lowFilter=Mat::zeros(1,N,CV_32F);
 98         _highFilter=Mat::zeros(1,N,CV_32F);
 99 
100         for (int i=0;i<N;i++)
101         {
102             _lowFilter.at<float>(0,i)=l[i];
103             _highFilter.at<float>(0,i)=h[i];
104         }
105     }
106     
107 }
108 

109 //小波分解
110 Mat WaveTransform::waveletDecompose( const Mat &_src, const Mat &_lowFilter, const Mat &_highFilter )
111 {
112     assert(_src.rows==1 && _lowFilter.rows==1 && _highFilter.rows ==1);
113     assert(_src.cols>=_lowFilter.cols && _src.cols>=_highFilter.cols );
114     Mat &src=Mat_<float>(_src);
115 
116     int D=src.cols;
117 
118     Mat &lowFilter=Mat_<float>(_lowFilter);
119     Mat &highFilter=Mat_<float>(_highFilter);
120 
121     //频域滤波或时域卷积；ifft( fft(x) * fft(filter)) = cov(x,filter) 
122     Mat dst1=Mat::zeros(1,D,src.type());
123     Mat dst2=Mat::zeros(1,D,src.type());
124 
125     filter2D(src,dst1,-1,lowFilter);
126     filter2D(src,dst2,-1,highFilter);
127 
128     //下采样
129     Mat downDst1=Mat::zeros(1,D/2,src.type());
130     Mat downDst2=Mat::zeros(1,D/2,src.type());
131 
132     resize(dst1,downDst1,downDst1.size());
133     resize(dst2,downDst2,downDst2.size());
134 
135     //数据拼接
136     for (int i=0;i<D/2;i++)
137     {
138         src.at<float>(0,i)=downDst1.at<float>(0,i);
139         src.at<float>(0,i+D/2)=downDst2.at<float>(0,i);
140 
141     }
142     return src;
143 }

用main函数调用WDT

Mat imgWave=m_waveTransform.WDT(src,"haar",3);
imshow("img",Mat_<uchar>(imgWave));
waitKey();

用一张考拉图来分析小波变换过程：

原图：

3层小波变换结果图（图片有压缩）：

下面逐一分析：

1 只做完小波行变换

2 行列变换

3 再次行变换

4 再次行列变换

三次之后到最后的分解图。

代码来自：http://shijuanfeng.blogbus.com/logs/221385402.html

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