OpenCV繪制灰度直方圖

代碼之一

1. #include <cv.h>   
2. #include <highgui.h>   
3. #pragma comment( lib, "cv.lib" )   
4. #pragma comment( lib, "cxcore.lib" )   
5. #pragma comment( lib, "highgui.lib" )   
6. int main()  
7. {  
8.          IplImage* src=cvLoadImage("lena.jpg",0);  
9.          int width=src->width;  
10.          int height=src->height;  
11.          int step=src->widthStep;  
12.          uchar* data=(uchar *)src->imageData;  
13.          int hist[256]={0};  
14.          for(int i=0;i<height;i++)  
15.          {  
16.                    for(int j=0;j<width;j++)  
17.                    {  
18.                             hist[data[i*step+j]]++;  
19.                    }  
20.          }  
21.          int max=0;  
22.          for(i=0;i<256;i++)  
23.          {  
24.                    if(hist[i]>max)  
25.                    {  
26.                             max=hist[i];  
27.                    }  
28.          }  
29.          IplImage* dst=cvCreateImage(cvSize(400,300),8,3);  
30.          cvSet(dst,cvScalarAll(255),0);  
31.          double bin_width=(double)dst->width/256;  
32.          double bin_unith=(double)dst->height/max;  
33.          for(i=0;i<256;i++)  
34.          {  
35.                    CvPoint p0=cvPoint(i*bin_width,dst->height);  
36.                    CvPoint p1=cvPoint((i+1)*bin_width,dst->height-hist[i]*bin_unith);  
37.                    cvRectangle(dst,p0,p1,cvScalar(0,255),-1,8,0);  
38.          }  
39.          cvNamedWindow("src",1);  
40.          cvShowImage("src",src);  
41.          cvNamedWindow("dst",1);  
42.          cvShowImage("dst",dst);  
43.          cvWaitKey(0);  
44.          cvDestroyAllWindows();  
45.          cvReleaseImage(&src);  
46.          cvReleaseImage(&dst);  
47.          return 0;  
48. }  

1. 代碼之二  

1. #include <cv.h>   
2. #include <highgui.h>   
3. #pragma comment( lib, "cv.lib" )   
4. #pragma comment( lib, "cxcore.lib" )   
5. #pragma comment( lib, "highgui.lib" )   
6. int main()  
7. {  
8.          IplImage* src=cvLoadImage("lena.jpg",0);  
9.          int size=256;  
10.          float range[]={0,255};  
11.          float* ranges[]={range};  
12.          CvHistogram* hist=cvCreateHist(1,&size,CV_HIST_ARRAY,ranges,1);  
13.          cvCalcHist(&src,hist,0,NULL);  
14.          float max=0;  
15.          cvGetMinMaxHistValue(hist,NULL,&max,NULL,NULL);  
16.          IplImage* dst=cvCreateImage(cvSize(400,300),8,3);  
17.          cvSet(dst,cvScalarAll(255),0);  
18.          double bin_width=(double)dst->width/size;  
19.          double bin_unith=(double)dst->height/max;  
20.          for(int i=0;i<size;i++)  
21.          {  
22.                    CvPoint p0=cvPoint(i*bin_width,dst->height);  
23.                    CvPoint p1=cvPoint((i+1)*bin_width,dst->height-cvGetReal1D(hist->bins,i)*bin_unith);  
24.                    cvRectangle(dst,p0,p1,cvScalar(0,255),-1,8,0);  
25.          }  
26.          cvNamedWindow("src",1);  
27.          cvShowImage("src",src);  
28.          cvNamedWindow("dst",1);  
29.          cvShowImage("dst",dst);  
30.          cvWaitKey(0);  
31.          cvDestroyAllWindows();  
32.          cvReleaseImage(&src);  
33.          cvReleaseImage(&dst);  
34.          return 0;  
35. }