OpenCV绘制灰度直方图
OpenCV绘制灰度直方图
代码之一
- #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;
- }
- 代码之二
- #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;
- }
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