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hist

	b_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。