c++ - 如何在opencv中找到图像中像素之间的欧氏距离

Question

int main(){
    Mat cmp, Ref, Diff;
    cmp = imread("image1.tif", CV_LOAD_IMAGE_UNCHANGED);
    Ref = imread("image2.tif", CV_LOAD_IMAGE_UNCHANGED);
    ShiftChk(cmp, Ref);
    absdiff(cmp, Ref, Diff);
    imshow("difference image", Diff);
    waitKey(0);
    double min, max;
    minMaxLoc(Diff, &min, &max);
    Point min_loc, max_loc;
    minMaxLoc(Diff, &min, &max, &min_loc, &max_loc);
    Size sz = Diff.size();
    cout << "max val : " << max << endl;//5
    cout << "max val: " << max_loc << endl; //[26,38]


    vector<vector<double>>test;
    for (int i = 0; i < Diff.cols; i++) {
        for (int j = 0; j < Diff.rows; j++) {

            Point difference = Diff.at<uchar>(26, 38) - Diff.at<uchar>(j, i);
            double dist = sqrt(difference.x*difference.x + difference.y*difference.y);              
            test.push_back(dist);
        }
    }
}

我试图找到图像中单个点与所有其他像素之间的欧氏距离。距离值将存储在 vector 测试中，但它显示出一些错误。而且我也不知道我使用的逻辑是否正确以给出正确的答案(欧氏距离)。谁能帮我吗。提前致谢

错误信息是:

error C2664: 
'void std::vector<std::vector<double,std::allocator<_Ty>>,std::allocator<std::vector<_Ty,std::allocator<_Ty>>>>::push_back(const std::vector<_Ty,std::allocator<_Ty>> &)' : 
cannot convert argument 1 from 'double' to 'std::vector<double,std::allocator<_Ty>> &&' 

Answer 1

主要有两个问题:

1. 您错误地将值附加到 test vector 。您需要创建一个中间 vector 并将其push_back 以测试(如 @0X0nosugar answer 所示)，或者更好地使用正确的维度初始化您的 vector 并将值放在正确的地方。

   vector<vector<double>> test(Diff.rows, vector<double>(Diff.cols));
   for (int i = 0; i < Diff.rows; i++) {
       for (int j = 0; j < Diff.cols; j++) {
           test[i][j] = ...       
       }
   }
   

   如上面的代码片段所示，按行扫描更好(也更快)，因为 OpenCV 按行存储图像。

2. 您不是在计算两点之间的距离。实际上，您正在获取两个给定点的值的差异，并从中创建一个 Point 对象(这没有意义)。您也可以避免显式计算欧氏距离。您可以使用 cv::norm:

    test[i][j] = norm(Point(38, 26) - Point(j, i)); // Pay attention to i,j order!
   

放在一起:

Point ref(38, 26);
vector<vector<double>> test(Diff.rows, vector<double>(Diff.cols));
for (int i = 0; i < Diff.rows; i++) {
    for (int j = 0; j < Diff.cols; j++) {
        test[i][j] = norm(ref - Point(j,i));      
    }
}