9.3 直方图对比
9.3.1 对比直方图:compareHist()函数
1.作用:
比较两幅直方图
2.函数原型:
(1)double compareHist(InputArray H1,InputArray H2, int method)
(2)double compareHist(const SpareMat& H1, const SpareMat& H2, int method)
3.参数说明:
(1)直方图1
(2)直方图2
(3)距离标准,4种,其中Correlation和Intersection标准值越大表示相似度越高:
1)相关,Correlation(method=CV_COMP_CORREL)
其中:
N等于直方图中bin的个数
2)卡方,Chi-Square(method=CV_COMP_CHISQR)
3)直方图相交,Intersection(method-CV_COMP_INTERSECT)
4)Bhattacharyya距离,(method=CV_COMP_BHATTACHARYYA)
Bhattacaryya距离与Hellinger距离相关,也可写作method=CV_COMP_HELLINGER
9.3.2 示例程序
#include<opencv2/opencv.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
using namespace cv;
int main()
{
//【1】声明储存基准图像和另外两张对比图象的矩阵(RGB和HSV)
Mat srcImage_base, hsvImage_base;
Mat srcImage_test1, hsvImage_test1;
Mat srcImage_test2, hsvImage_test2;
Mat hsvImage_halfDown;
//【2】载入基准图像和两张测试图像并显示
srcImage_base = imread("1.jpg", 1);
srcImage_test1 = imread("2.jpg", 1);
srcImage_test2 = imread("3.jpg", 1);
imshow("基准图像", srcImage_base);
imshow("测试图像1", srcImage_test1);
imshow("测试图像2", srcImage_test2);
//【3】将图像由BGR色彩空间转换到HSV色彩空间
cvtColor(srcImage_base, hsvImage_base, COLOR_RGB2HSV);
cvtColor(srcImage_test1, hsvImage_test1, COLOR_RGB2HSV);
cvtColor(srcImage_test2, hsvImage_test2, COLOR_RGB2HSV);
//【4】创建包含基准图像下半部的半身图像(HSV格式)
hsvImage_halfDown = hsvImage_base(Range(hsvImage_base.rows / 2, hsvImage_base.rows - 1), Range(0, hsvImage_base.cols - 1));
//【5】初始化计算直方图需要的实参
//对hue通道使用30个bin,对saturation通道使用32个bin
int h_bins = 50;
int s_bins = 60;
int histSize[] = { h_bins,s_bins };
//hue取值范围0-256,saturation取值范围0-180
float h_ranges[] = { 0,256 };
float s_ranges[] = { 0,180 };
const float* ranges[] = { h_ranges,s_ranges };
//使用第0和1通道
int channels[] = { 0,1 };
//【6】创建存储直方图的MatND类实例
MatND baseHist, testHist1, testHist2, halfDownHist;
//【7】计算基准图像,两张测试图像,半身基准图像的HSV直方图
calcHist(&hsvImage_base, 1, channels, Mat(), baseHist, 2, histSize, ranges, true, false);
normalize(baseHist, baseHist, 0, 1, NORM_MINMAX, -1, Mat());
calcHist(&hsvImage_test1, 1, channels, Mat(), testHist1, 2, histSize, ranges, true, false);
normalize(testHist1, testHist1, 0, 1, NORM_MINMAX, -1, Mat());
calcHist(&hsvImage_test2, 1, channels, Mat(), testHist2, 2, histSize, ranges, true, false);
normalize(testHist2, testHist2, 0, 1, NORM_MINMAX, -1, Mat());
calcHist(&hsvImage_halfDown, 1, channels, Mat(), halfDownHist, 2, histSize, ranges, true, false);
normalize(halfDownHist, halfDownHist, 0, 1, NORM_MINMAX, -1, Mat());
//【8】按顺序使用4种对比标准将基准图像的直方图与其余各直方图进行对比
for (int i = 0; i < 4; i++)
{
//进行图像直方图的对比
int compare_method = i;
double base_base = compareHist(baseHist, baseHist, compare_method);
double base_test1 = compareHist(baseHist, testHist1, compare_method);
double base_test2 = compareHist(baseHist, testHist2, compare_method);
double base_half = compareHist(baseHist, halfDownHist, compare_method);
//输出结果
printf("方法[%d]的匹配结果如下:\n\n【基准图-基准图】:%f,【基准图-测试图1】:%f,【基准图-测试图2】:%f,【基准图-半身图】:%f\n", i, base_base, base_test1, base_test2, base_half);
printf("----------------------------------------------------------------------------------------------------------------------------------\n");
}
printf("检测结束\n");
waitKey(0);
return 0;
}
运行效果: