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. }