opencv绘制灰度直方图

#include <cv.h>
#include <highgui.h>
#pragma comment( lib, "cv.lib" )
#pragma comment( lib, "cxcore.lib" )
#pragma comment( lib, "highgui.lib" )
int main()
{
IplImage* src=cvLoadImage("lena.jpg",0);
int width=src->width;
int height=src->height;
int step=src->widthStep;
uchar* data=(uchar *)src->imageData;
int hist[256]={0};
for(int i=0;i<height;i++)
{
for(int j=0;j<width;j++)
{
hist[data[i*step+j]]++;
}
}
int max=0;
for(i=0;i<256;i++)
{
if(hist[i]>max)
{
max=hist[i];
}
}
IplImage* dst=cvCreateImage(cvSize(400,300),8,3);
cvSet(dst,cvScalarAll(255),0);
double bin_width=(double)dst->width/256;
double bin_unith=(double)dst->height/max;
for(i=0;i<256;i++)
{
CvPoint p0=cvPoint(i*bin_width,dst->height);
CvPoint p1=cvPoint((i+1)*bin_width,dst->height-hist[i]*bin_unith);
cvRectangle(dst,p0,p1,cvScalar(0,255),-1,8,0);
}
cvNamedWindow("src",1);
cvShowImage("src",src);
cvNamedWindow("dst",1);
cvShowImage("dst",dst);
cvWaitKey(0);
cvDestroyAllWindows();
cvReleaseImage(&src);
cvReleaseImage(&dst);
return 0;
}

#include <cv.h>
#include <highgui.h>
#pragma comment( lib, "cv.lib" )
#pragma comment( lib, "cxcore.lib" )
#pragma comment( lib, "highgui.lib" )
int main()
{
IplImage* src=cvLoadImage("lena.jpg",0);
int size=256;
float range[]={0,255};
float* ranges[]={range};
CvHistogram* hist=cvCreateHist(1,&size,CV_HIST_ARRAY,ranges,1);
cvCalcHist(&src,hist,0,NULL);
float max=0;
cvGetMinMaxHistValue(hist,NULL,&max,NULL,NULL);
IplImage* dst=cvCreateImage(cvSize(400,300),8,3);
cvSet(dst,cvScalarAll(255),0);
double bin_width=(double)dst->width/size;
double bin_unith=(double)dst->height/max;
for(int i=0;i<size;i++)
{
CvPoint p0=cvPoint(i*bin_width,dst->height);
CvPoint p1=cvPoint((i+1)*bin_width,dst->height-cvGetReal1D(hist->bins,i)*bin_unith);
cvRectangle(dst,p0,p1,cvScalar(0,255),-1,8,0);
}
cvNamedWindow("src",1);
cvShowImage("src",src);
cvNamedWindow("dst",1);
cvShowImage("dst",dst);
cvWaitKey(0);
cvDestroyAllWindows();
cvReleaseImage(&src);
cvReleaseImage(&dst);
return 0;
}