opencv 二维直方图

#define cvCvtPixToPlane cvSplit
#define cvCvtPlaneToPix cvMerge

void hist_2D(void)
{
IplImage *src=cvLoadImage("lena.jpg");
IplImage *hsv=cvCreateImage(cvGetSize(src), IPL_DEPTH_8U, 3);
cvCvtColor(src, hsv, CV_BGR2HSV_FULL);

IplImage *h_plane=cvCreateImage(cvGetSize(src), IPL_DEPTH_8U, 1);
IplImage *s_plane=cvCreateImage(cvGetSize(src), IPL_DEPTH_8U, 1);
IplImage *v_plane=cvCreateImage(cvGetSize(src), IPL_DEPTH_8U, 1);
IplImage *planes[]={h_plane, s_plane};
cvCvtPixToPlane(hsv, h_plane, s_plane, v_plane, 0);

//Build the histogram and compute its contents.
int h_bins=256, s_bins=256;
CvHistogram *hist;
{
int hist_size[]={h_bins, s_bins};
float h_ranges[]={0, 255}; //hue is [0, 180]
float s_ranges[]={0, 255};
float* ranges[]={h_ranges, s_ranges};
hist=cvCreateHist(2, hist_size, CV_HIST_ARRAY, ranges, 1);
}
cvCalcHist(planes, hist, 0, 0); //Compute histogram
cvNormalizeHist(hist, 1.0); //Normalize it
//Create an image to use to visualize our histogram
int scale=2;
IplImage *hist_img=cvCreateImage(cvSize(h_bins*scale, s_bins*scale), IPL_DEPTH_8U, 3);
cvZero(hist_img);

//populate our visualization with little gray squares.
float max_value=0;
cvGetMinMaxHistValue(hist, 0, &max_value, 0, 0);
for (int h=0; h<h_bins; h++)
{
for (int s=0; s<s_bins; s++)
{
float bin_val=cvQueryHistValue_2D(hist, h, s);
int intensity=cvRound(bin_val*255/max_value);
cvRectangle(hist_img, cvPoint(h*scale, s*scale), cvPoint((h+1)*scale-1, (s+1)*scale-1), CV_RGB(intensity, intensity, intensity), CV_FILLED);
}
}

cvNamedWindow("Source");
cvShowImage("Source", src);

cvNamedWindow("H-S Histogram");
cvShowImage("H-S Histogram", hist_img);

cvWaitKey(0);
}