OpenCV2马拉松第12圈——直方图比较

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• 使用4种不同的方法进行直方图比较

葵花宝典

要比较两个直方图, 首先必须要选择一个衡量直方图相似度的对比标准。也就是先说明要在哪个方面做对比。

我们可以想出很多办法，OpenCV采用了以下4种

公式也都不难，我们自己就能实现。

d越小，表示差异越低，两幅图像越接近，越相似

初识API

C++:  double  compareHist (InputArray  H1, InputArray  H2, int  method )

C++:  double  compareHist (const SparseMat&  H1, const SparseMat&  H2, int  method )

	H1 – First compared histogram. H2 – Second compared histogram of the same size as H1 . method – Comparison method that could be one of the following: CV_COMP_CORREL Correlation CV_COMP_CHISQR Chi-Square CV_COMP_INTERSECT Intersection CV_COMP_BHATTACHARYYA Bhattacharyya distance CV_COMP_HELLINGER Synonym for CV_COMP_BHATTACHARYYA

荷枪实弹

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>

using namespace std;
using namespace cv;

int main( int, char** argv )
{
	Mat src1,src2,gray1,gray2;
	src1 = imread(argv[1]);
	src2 = imread(argv[2]); 
	cvtColor(src1, gray1, CV_BGR2GRAY);
	cvtColor(src2, gray2, CV_BGR2GRAY);
	
	int histSize = 256;
  	float range[] = { 0, 256 } ;
  	const float* histRange = { range };
 	int channels[] = {0};
 	
 	Mat hist1,hist2;
	calcHist( &gray1, 1, channels, Mat(), hist1, 1, &histSize, &histRange);
	calcHist( &gray2, 1, channels, Mat(), hist2, 1, &histSize, &histRange);

	//相关：CV_COMP_CORREL    
	//卡方：CV_COMP_CHISQR
	//直方图相交：CV_COMP_INTERSECT
	//Bhattacharyya距离：CV_COMP_BHATTACHARYYA
	double diff = compareHist(hist1,hist2,CV_COMP_BHATTACHARYYA);
	cout << diff << endl;
}

举一反三

这篇直方图比较非常简单，没什么要说的了

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