在使用鼠标绘制的线中收集像素值

Question

我有一张图像（24位bmp），如下所示：

用户使用鼠标绘制一条线（此处以红色显示）。这条线可以是任何角度的任何地方。然后他点击鼠标右键或左键，除了在控制台上显示外，线上的图像像素值也存储在文件中。

我使用setMouseCallback()来显示鼠标的位置（如下所示）。但是我需要更多帮助来理解在线上查找和存储像素值的优雅方式。请帮忙！

void CallBackFunc(int event, int x, int y, int flags, void* userdata)
{
     if  ( event == EVENT_LBUTTONDOWN )
     {
          cout << "Left button of the mouse is clicked - position (" << x << ", " << y << ")" << endl;
     }
     else if  ( event == EVENT_RBUTTONDOWN )
     {
          cout << "Right button of the mouse is clicked - position (" << x << ", " << y << ")" << endl;
     }

     else if ( event == EVENT_MOUSEMOVE )
     {
          cout << "Mouse move over the window - position (" << x << ", " << y << ")" << endl;

     }
}

int main(int argc, char** argv)
{

     Mat img = imread("C:\\Users\\Acme\\Desktop\\image-processing\\2.bmp");
     namedWindow(" Window", 1);
     setMouseCallback(" Window", CallBackFunc, NULL);
     imshow(" Window", img);
     waitKey(0);
     return 0;

}

Answer 1

通过翘曲将线提取到1 x（线长）或（线长）x 1，垂直或水平Mat。然后，您可以轻松读取或跨越像素值。

Answer 2

具体细节取决于您的程序，但一旦点击两个点，就会填充值。之后你做的事由你决定。

cv::Point g_points[2];
int g_pointIndex;
std::vector<cv::Vec3b> values;
bool g_allGood = false;

void onMouse(int e, int x, int y, int d, void* ud)
{
    if (e != CV_EVENT_LBUTTONDOWN || g_pointIndex >= 2)
        return;

    g_points[g_pointIndex++] = cv::Point(x, y);
}

void main()
{
    // load image as greyscale
    Mat img = imread("C:\\temp\\2.png", CV_8UC1);
    namedWindow("img", 1);

    setMouseCallback("img", onMouse);

    while (1)
    {
        // all points collected
        if (g_pointIndex == 2 && !g_allGood)
        {
            /*
            to save processing, i suggest you remove the mouse callback once all points
            are collected. do this with: setMouseCallback("img", NULL,NULL);
            */

            // create line iterator, and add pixel values to values vector
            cv::LineIterator it(img, g_points[0], g_points[1]);

            for (int i = 0; i < it.count; i++, ++it)
                values.push_back((Vec3b)*it);

            // you now have all pixel values in values;
            g_allGood = true;
        }

        imshow("img", img);
        waitKey(100);
    }

}