１直方图计算样例如下：

vector<Mat> getimhist(Mat im)
{
	vector<Mat> ims;
	split(im, ims);
	const int binnum[1] = {256};
	float valuerange[2] = { 0,255 };
	const float* hrange[1] = { valuerange };
	vector<Mat> imhist;
	int chnum=ims.size();
	for(int i = 0; i <chnum; i++)
	{
		Mat hist;
		calcHist(&ims[i],1,0, Mat(), hist,1,binnum,hrange);
		normalize(hist, hist, 1,0, NORM_L2, -1);
		imhist.push_back(hist);
	}

	return imhist;
}

这个函数既可以计算灰度图的也可以计算彩色图．

２直方图比较如下：

Mat vectmat2mat(vector<Mat> ims)
{
	Mat bigim=ims[0];
	for (int i = 1; i <ims.size(); i++)
	{
		bigim.push_back(ims[i]);
	}

	return bigim;
}

float get2imhistsim(Mat im1,Mat im2)
{
	vector<Mat> imhist1=getimhist(im1);
	vector<Mat> imhist2=getimhist(im2);
	Mat hist1=vectmat2mat(imhist1);
	Mat hist2=vectmat2mat(imhist2);
	float histsim = compareHist(hist1, hist2, 0);

	return histsim;
}