OpenCV——彩色图像转成灰度图像

// PS_Algorithm.h

#ifndef PS_ALGORITHM_H_INCLUDED

#define PS_ALGORITHM_H_INCLUDED

#include <iostream>

#include <string>

#include "cv.h"

#include "highgui.h"

#include "cxmat.hpp"

#include "cxcore.hpp"

using namespace std;

using namespace cv;

#endif // PS_ALGORITHM_H_INCLUDED

/*

The program will transfor the color

image to the gray image.

The image must be color image.

*/



#include "PS_Algorithm.h"

int main()

{

    string  Image_name("2.jpg");

    Mat Image=imread(Image_name.c_str());

    Mat Image_test(Image.size(),CV_32FC3);

    Image.convertTo(Image_test, CV_32FC3);

    Mat Gray_img(Image_test.size(), CV_32FC1);

    Mat r,g,b;

    Gray_img.copyTo(r);

    g=r;

    b=r;

    Mat bgr[]={b,g,r};

    split(Image_test, bgr);

    b=bgr[0];

    g=bgr[1];

    r=bgr[2];

    Mat I1,I2,I3;

    I1=r;

    I2=r;

    I3=r;



    // I=0.299*R+0.587*G+0.144*B   方案一

    Gray_img=(0.299*r+0.587*g+0.144*b);

    I1=Gray_img/255;

    imshow("I1", I1);



    // I=(R+G+B)/3  方案二

    Gray_img=(0.333*r+0.333*g+0.333*b);

    I2=Gray_img/255;

    for(int i=100; i<105; i++)

        for(int j=100; j<105; j++)

            cout<<I2.at<float>(i,j)<<endl;

    imshow ("I2", I2);



    // I=max(R,G,B)   方案三

    float *p1,*p2,*p3,*p;

    p1=r.ptr<float>(0);

    p2=g.ptr<float>(0);

    p3=b.ptr<float>(0);

    p=I3.ptr<float>(0);

    int nums;

    nums=Gray_img.rows*Gray_img.cols;

    for (int i=0; i<nums; i++)

        p[i]=max(p1[i],max(p2[i],p3[i]))/255;

    imshow("I3",I3);



    cout<<"All is well."<<endl;

    waitKey();

}