OpenCV--图像的反色与灰度图显示

对于单通道图像：

void Invert1(){    Mat src,dest;    src = imread("lena.jpg");    if(!src.data){        cout << "图像载入失败" << endl;        return ;    }    namedWindow("原图像",CV_WINDOW_AUTOSIZE);    imshow("原图像",src);    cvtColor(src,dest,COLOR_BGR2GRAY);    int rows = src.rows;    int cols = src.cols;    //单通道图像的反色    for(int row = 0;row<rows;row++){        for(int col = 0;col<cols;col++){            dest.at<uchar>(row,col) = 255 - dest.at<uchar>(row,col);        }    }    namedWindow("单通道，反色后",CV_WINDOW_AUTOSIZE);    imshow("单通道，反色后",dest);    cvWaitKey();}

对于三通道图像：

void Invert2(){    Mat src;    src = imread("lena.jpg");    if(!src.data){        cout << "图像载入失败" << endl;        return ;    }    namedWindow("原图像",CV_WINDOW_AUTOSIZE);    imshow("原图像",src);    int rows = src.rows;    int cols = src.cols;    cout << rows << "\t" << cols << endl;    Mat dest;    dest.create(src.size(),src.type());    for(int row = 0;row<rows;row++){        for(int col=0;col<cols;col++){            int b = src.at<Vec3b>(row,col)[0];            int g = src.at<Vec3b>(row,col)[1];            int r = src.at<Vec3b>(row,col)[2];            dest.at<Vec3b>(row,col)[0] = 255-b;            dest.at<Vec3b>(row,col)[1] = 255-g;            dest.at<Vec3b>(row,col)[2] = 255-r;        }    }    namedWindow("三通道，反色后",CV_WINDOW_AUTOSIZE);    imshow("三通道，反色后",dest);    cvWaitKey();}

OpenCV提供的函数bitwise_not(src,dest):

void Invert3(){    Mat src,dest;    src = imread("lena.jpg");    if(!src.data){        cout << "图像载入失败" << endl;        return ;    }    namedWindow("原图像",CV_WINDOW_AUTOSIZE);    imshow("原图像",src);    cv::bitwise_not(src,dest);    namedWindow("反色后",CV_WINDOW_AUTOSIZE);    imshow("反色后",dest);    cvWaitKey();}

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不同于使用cvtColor()函数，我们可以自己对像素操作实现灰度图的显示：

void GrayShow(){    Mat src;    src = imread("lena.jpg");    if(!src.data){        cout << "图像载入失败" << endl;        return ;    }    namedWindow("原图像",CV_WINDOW_AUTOSIZE);    imshow("原图像",src);    int rows = src.rows;    int cols = src.cols;    Mat dest  = Mat(src.rows,src.cols,0);    for(int row = 0;row<rows;row++){        for(int col=0;col<cols;col++){            int b = src.at<Vec3b>(row,col)[0];            int g = src.at<Vec3b>(row,col)[1];            int r = src.at<Vec3b>(row,col)[2];            dest.at<uchar>(row,col) = max(r,max(g,b));//选择bgr中最大值            //dest.at<uchar>(row,col) = min(r,min(g,b));//选择bgr中最小值        }    }    namedWindow("min,灰度图",CV_WINDOW_AUTOSIZE);    imshow("min,灰度图",dest);    cvWaitKey();}