直方图（下）

// 直方图的RGB.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "opencv2/opencv.hpp"#define cvQueryHistValue_1D( hist, idx0 ) \    ((float)cvGetReal1D( (hist)->bins, (idx0)))IplImage* DrawHistogram(CvHistogram* hist, int scaleX= 1, int scaleY= 1)   {     float histMax= 0;   cvGetMinMaxHistValue(hist, 0, &histMax, 0, 0);  //获取直方图的最大值   if(!histMax)   {   histMax= 1;        }   IplImage* imgHist= cvCreateImage(cvSize(256* scaleX, 64* scaleY), 8, 1);   cvZero(imgHist);     //置零   for(int i=0; i< 255; i++)   {        float histValue= cvQueryHistValue_1D(hist, i);   //获取第i个bin 的值float nextValue= cvQueryHistValue_1D(hist, i+1);CvPoint pt1= cvPoint((i+ 100)* scaleX, 64* scaleY);  //构建四个点CvPoint pt2= cvPoint((i+ 101)* scaleX, 64* scaleY);CvPoint pt3= cvPoint((i+101)* scaleX, (int )((1- nextValue/ histMax)* 64* scaleY));CvPoint pt4= cvPoint((i+ 100)* scaleX, (int)((1-histValue/ histMax)* 64* scaleY));            int numPts= 5;CvPoint pts[5];pts[0]= pt1;pts[1]= pt2;pts[2]= pt3;pts[3]= pt4;pts[4]= pt1;cvFillConvexPoly(imgHist, pts, numPts, cvScalar(255));   }   return imgHist;   }int _tmain(int argc, _TCHAR* argv[]){ IplImage* src0= cvLoadImage("F://Opencv_picture\\05.jpg");IplImage* src= cvCreateImage(cvGetSize(src0), IPL_DEPTH_8U, 3);cvConvertScale(src0, src, 1.0, 0);cvNamedWindow("Histogram");cvShowImage("Histogram", src);int dims= 1; //直方图的维度、int sizes = 256; //直方图数据个数float range[]= {0, 255}; //直方图每个维度取值范围float * ranges[]= {range};CvHistogram* hist;hist= cvCreateHist(dims, &sizes, CV_HIST_ARRAY, ranges, 1);cvClearHist(hist);IplImage* b_img= cvCreateImage(cvGetSize(src), 8, 1);IplImage* g_img= cvCreateImage(cvGetSize(src), 8, 1);IplImage* r_img= cvCreateImage(cvGetSize(src), 8, 1);cvSplit(src, b_img, g_img, r_img, NULL);   //分解图像到三个图像的内存空间cvCalcHist(&b_img, hist, 0, 0);    // 统计一个通道的数据额到histb_img= DrawHistogram(hist);cvClearHist(hist);cvCalcHist(&b_img, hist, 0, 0); g_img= DrawHistogram(hist);cvClearHist(hist);cvCalcHist(&r_img, hist, 0, 0);r_img= DrawHistogram(hist);cvClearHist(hist);cvNamedWindow("B");cvNamedWindow("G");cvNamedWindow("R");     cvShowImage("B", b_img); cvShowImage("G", g_img); cvShowImage("R", r_img); cvWaitKey(0); cvReleaseImage(&src); cvReleaseImage(&r_img); cvReleaseImage(&b_img);      cvReleaseImage(&g_img);  cvDestroyWindow("Histogram");  cvDestroyWindow("B");  cvDestroyWindow("G");  cvDestroyWindow("R");return 0;}

FillConvexPoly
填充凸多边形

void cvFillConvexPoly( CvArr* img, CvPoint* pts, int npts,
CvScalar color, int line_type=8, int shift=0 );
img
图像。
pts
指向单个多边形的指针数组。
npts
多边形的顶点个数。
color
多边形的颜色。
line_type
组成多边形的线条的类型。参见cvLine
shift
顶点坐标的小数点位数。
　

函数cvFillConvexPoly填充凸多边形内部。这个函数比函数cvFillPoly 更快。它除了可以填充凸多边形区域还可以填充任何的单调多边形。例如：一个被水平线（扫描线）至多两次截断的多边形。