OpenCV Jpeg编解码

// JPEGDecodeEncode.cpp : 定义控制台应用程序的入口点。

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <cv.h>
#include <highgui.h>
using namespace std;
using namespace cv;

double getPSNR(Mat& src1, Mat& src2, int bb=0);

int main(int argc, char** argv)
{
Mat src = imread("lena.png");
cout<<"origin image size: "<<src.dataend-src.datastart<<endl;
cout<<"height: "<<src.rows<<endl<<"width: "<<src.cols<<endl<<"depth: "<<src.channels()<<endl;
cout<<"height*width*depth: "<<src.rows*src.cols*src.channels()<<endl<<endl;
//(1) jpeg compression
vector<uchar> buff;//buffer for coding
vector<int> param = vector<int>(2);
param[0]=CV_IMWRITE_JPEG_QUALITY;
param[1]=95;//default(95) 0-100

imencode(".jpg",src,buff,param);
cout<<"coded file size(jpg): "<<buff.size()<<endl;//fit buff size automatically.
Mat jpegimage = imdecode(Mat(buff),CV_LOAD_IMAGE_COLOR);

//(2) png compression
param[0]=CV_IMWRITE_PNG_COMPRESSION;
param[1]=3;//default(3)  0-9.
imencode(".png",src,buff,param);
cout<<"coded file size(png): "<<buff.size()<<endl;
Mat pngimage = imdecode(Mat(buff),CV_LOAD_IMAGE_COLOR);

//(3) intaractive jpeg compression
char name[64];
namedWindow("jpg");
int q=95;
createTrackbar("quality","jpg",&q,100);
int key = 0;
while(key!='q')
{
param[0]=CV_IMWRITE_JPEG_QUALITY;
param[1]=q;
imencode(".jpg",src,buff,param);
Mat show = imdecode(Mat(buff),CV_LOAD_IMAGE_COLOR);

double psnr = getPSNR(src,show);//get PSNR
double bpp = 8.0*buff.size()/(show.size().area());//bit/pixe;
sprintf(name,"quality:%03d, %.1fdB, %.2fbpp",q,psnr,bpp);
putText(show,name,Point(15,50), FONT_HERSHEY_SIMPLEX,1,CV_RGB(255,255,255),2);
imshow("jpg",show);
key = waitKey(33);

if(key =='s')
{
//(4) data writing
sprintf(name,"q%03d_%.2fbpp.png",q,bpp);
imwrite(name,show);

sprintf(name,"q%03d_%.2fbpp.jpg",q,bpp);
param[0]=CV_IMWRITE_JPEG_QUALITY;
param[1]=q;
imwrite(name,src,param);;
}
}
}
double getPSNR(Mat& src1, Mat& src2, int bb)
{
int i,j;
double sse,mse,psnr;
sse = 0.0;

Mat s1,s2;
cvtColor(src1,s1,CV_BGR2GRAY);
cvtColor(src2,s2,CV_BGR2GRAY);

int count=0;
for(j=bb;j<s1.rows-bb;j++)
{
uchar* d=s1.ptr(j);
uchar* s=s2.ptr(j);

for(i=bb;i<s1.cols-bb;i++)
{
sse += ((d[i] - s[i])*(d[i] - s[i]));
count++;
}
}
if(sse == 0.0 || count==0)
{
return 0;
}
else
{
mse =sse /(double)(count);
psnr = 10.0*log10((255*255)/mse);
return psnr;
}
}