结合网络上的资料和自己的修改，实现了psnr和ssim的c++版本。

#include<iostream>
#include<opencv2\opencv.hpp>
#include <math.h> 
#include <stdio.h> 
#include <cv.h>	
#include <highgui.h>
using std::cout;
using std::endl;
int ssim(char *ref_image, char *obj_image)
{
	// default settings
	double C1 = 6.5025, C2 = 58.5225;

	IplImage
		*img1 = NULL, *img2 = NULL, *img1_img2 = NULL,
		*img1_temp = NULL, *img2_temp = NULL,
		*img1_sq = NULL, *img2_sq = NULL,
		*mu1 = NULL, *mu2 = NULL,
		*mu1_sq = NULL, *mu2_sq = NULL, *mu1_mu2 = NULL,
		*sigma1_sq = NULL, *sigma2_sq = NULL, *sigma12 = NULL,
		*ssim_map = NULL, *temp1 = NULL, *temp2 = NULL, *temp3 = NULL;


	/***************************** INITS **********************************/
	img1_temp = cvLoadImage(ref_image);
	img2_temp = cvLoadImage(obj_image);

	if (img1_temp == NULL || img2_temp == NULL)
		return -1;

	int x = img1_temp->width, y = img1_temp->height;
	int nChan = img1_temp->nChannels, d = IPL_DEPTH_32F;
	CvSize size = cvSize(x, y);

	img1 = cvCreateImage(size, d, nChan);
	img2 = cvCreateImage(size, d, nChan);

	cvConvert(img1_temp, img1);
	cvConvert(img2_temp, img2);
	cvReleaseImage(&img1_temp);
	cvReleaseImage(&img2_temp);


	img1_sq = cvCreateImage(size, d, nChan);
	img2_sq = cvCreateImage(size, d, nChan);
	img1_img2 = cvCreateImage(size, d, nChan);

	cvPow(img1, img1_sq, 2);
	cvPow(img2, img2_sq, 2);
	cvMul(img1, img2, img1_img2, 1);

	mu1 = cvCreateImage(size, d, nChan);
	mu2 = cvCreateImage(size, d, nChan);

	mu1_sq = cvCreateImage(size, d, nChan);
	mu2_sq = cvCreateImage(size, d, nChan);
	mu1_mu2 = cvCreateImage(size, d, nChan);


	sigma1_sq = cvCreateImage(size, d, nChan);
	sigma2_sq = cvCreateImage(size, d, nChan);
	sigma12 = cvCreateImage(size, d, nChan);

	temp1 = cvCreateImage(size, d, nChan);
	temp2 = cvCreateImage(size, d, nChan);
	temp3 = cvCreateImage(size, d, nChan);

	ssim_map = cvCreateImage(size, d, nChan);
	/*************************** END INITS **********************************/


	//////////////////////////////////////////////////////////////////////////
	// PRELIMINARY COMPUTING
	cvSmooth(img1, mu1, CV_GAUSSIAN, 11, 11, 1.5);
	cvSmooth(img2, mu2, CV_GAUSSIAN, 11, 11, 1.5);

	cvPow(mu1, mu1_sq, 2);
	cvPow(mu2, mu2_sq, 2);
	cvMul(mu1, mu2, mu1_mu2, 1);


	cvSmooth(img1_sq, sigma1_sq, CV_GAUSSIAN, 11, 11, 1.5);
	cvAddWeighted(sigma1_sq, 1, mu1_sq, -1, 0, sigma1_sq);

	cvSmooth(img2_sq, sigma2_sq, CV_GAUSSIAN, 11, 11, 1.5);
	cvAddWeighted(sigma2_sq, 1, mu2_sq, -1, 0, sigma2_sq);

	cvSmooth(img1_img2, sigma12, CV_GAUSSIAN, 11, 11, 1.5);
	cvAddWeighted(sigma12, 1, mu1_mu2, -1, 0, sigma12);


	//////////////////////////////////////////////////////////////////////////
	// FORMULA

	// (2*mu1_mu2 + C1)
	cvScale(mu1_mu2, temp1, 2);
	cvAddS(temp1, cvScalarAll(C1), temp1);

	// (2*sigma12 + C2)
	cvScale(sigma12, temp2, 2);
	cvAddS(temp2, cvScalarAll(C2), temp2);

	// ((2*mu1_mu2 + C1).*(2*sigma12 + C2))
	cvMul(temp1, temp2, temp3, 1);

	// (mu1_sq + mu2_sq + C1)
	cvAdd(mu1_sq, mu2_sq, temp1);
	cvAddS(temp1, cvScalarAll(C1), temp1);

	// (sigma1_sq + sigma2_sq + C2)
	cvAdd(sigma1_sq, sigma2_sq, temp2);
	cvAddS(temp2, cvScalarAll(C2), temp2);

	// ((mu1_sq + mu2_sq + C1).*(sigma1_sq + sigma2_sq + C2))
	cvMul(temp1, temp2, temp1, 1);

	// ((2*mu1_mu2 + C1).*(2*sigma12 + C2))./((mu1_sq + mu2_sq + C1).*(sigma1_sq + sigma2_sq + C2))
	cvDiv(temp3, temp1, ssim_map, 1);


	CvScalar index_scalar = cvAvg(ssim_map);

	// through observation, there is approximately 
	// 1% error max with the original matlab program

	cout << "(R, G & B SSIM index)" << std::endl;
	cout << index_scalar.val[2] << endl;
	cout << index_scalar.val[1] << endl;
	cout << index_scalar.val[0] << endl;

	cvReleaseImage(&img1_sq);
	cvReleaseImage(&img2_sq);
	cvReleaseImage(&img1_img2);
	cvReleaseImage(&mu1);
	cvReleaseImage(&mu2);
	cvReleaseImage(&mu1_sq);
	cvReleaseImage(&mu2_sq);
	cvReleaseImage(&mu1_mu2);
	cvReleaseImage(&sigma1_sq);
	cvReleaseImage(&sigma2_sq);
	cvReleaseImage(&sigma12);
	cvReleaseImage(&temp1);
	cvReleaseImage(&temp2);
	cvReleaseImage(&temp3);
	cvReleaseImage(&ssim_map);
	return 0;
}
double psnr(char *ref_image, char *obj_image)
{
	cv::Mat image_ref = cv::imread(ref_image);
	cv::Mat image_obj = cv::imread(obj_image);
	double mse = 0;
	double div_r=0;
	double div_g=0;
	double div_b=0;
	int width = image_ref.cols;
	int height = image_ref.rows;
	double psnr = 0;
	for (int v = 0; v < height; v++)
	{
		for (int u = 0; u < width; u++)
		{
			div_r = image_ref.at<cv::Vec3b>(v, u)[0] - image_obj.at<cv::Vec3b>(v, u)[0];
			div_g = image_ref.at<cv::Vec3b>(v, u)[1] - image_obj.at<cv::Vec3b>(v, u)[1];
			div_b = image_ref.at<cv::Vec3b>(v, u)[2] - image_obj.at<cv::Vec3b>(v, u)[2];
			mse += div_r*div_r + div_b*div_b + div_g*div_g;
            
		}
	}
	mse = mse / (width*height);
	psnr = 10 * log10(255 * 255 / mse);
	printf("%lf\n", mse);
	printf("%lf\n", psnr);
	return psnr;
}