c++ - OpenCV c++ hwnd2mat(截图)-> blobFromImage : Error

Question

我正在研究屏幕捕获对象识别系统。 我的代码:

#include "opencv2/imgproc.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/dnn.hpp"
#include <opencv2/core/utils/trace.hpp>
#include <Windows.h>
#include <iostream>


using namespace std;
using namespace cv;
using namespace cv::dnn;

Mat hwnd2mat(HWND hwnd) {
    HDC hwindowDC,hwindowCompatibleDC;

    int height,width,srcheight,srcwidth;
    HBITMAP hbwindow;
    Mat src;
    BITMAPINFOHEADER  bi;

    hwindowDC=GetDC(hwnd);
    hwindowCompatibleDC=CreateCompatibleDC(hwindowDC);
    SetStretchBltMode(hwindowCompatibleDC,COLORONCOLOR);

    RECT windowsize;    // get the height and width of the screen
    GetClientRect(hwnd, &windowsize);

    srcheight = windowsize.bottom;
    srcwidth = windowsize.right;
    height = windowsize.bottom/1;  //change this to whatever size you want to resize to
    width = windowsize.right/1;

    src.create(height,width,CV_8UC4);

    // create a bitmap
    hbwindow = CreateCompatibleBitmap( hwindowDC, width, height);
    bi.biSize = sizeof(BITMAPINFOHEADER);    //http://msdn.microsoft.com/en-us/library/windows/window/dd183402%28v=vs.85%29.aspx
    bi.biWidth = width;
    bi.biHeight = -height;  //this is the line that makes it draw upside down or not
    bi.biPlanes = 1;
    bi.biBitCount = 32;
    bi.biCompression = BI_RGB;
    bi.biSizeImage = 0;
    bi.biXPelsPerMeter = 0;
    bi.biYPelsPerMeter = 0;
    bi.biClrUsed = 0;
    bi.biClrImportant = 0;

    // use the previously created device context with the bitmap
    SelectObject(hwindowCompatibleDC, hbwindow);
    // copy from the window device context to the bitmap device context
    StretchBlt( hwindowCompatibleDC, 0,0, width, height, hwindowDC, 0, 0,srcwidth,srcheight, SRCCOPY); //change SRCCOPY to NOTSRCCOPY for wacky colors !
    GetDIBits(hwindowCompatibleDC,hbwindow,0,height,src.data,(BITMAPINFO *)&bi,DIB_RGB_COLORS);  //copy from hwindowCompatibleDC to hbwindow

    // avoid memory leak
    DeleteObject (hbwindow);
    DeleteDC(hwindowCompatibleDC);
    ReleaseDC(hwnd, hwindowDC);

    return src;
}

string CLASSES[] = {"background", "aeroplane", "bicycle", "bird", "boat",
"bottle", "bus", "car", "cat", "chair", "cow", "diningtable",
"dog", "horse", "motorbike", "person", "pottedplant", "sheep",
"sofa", "train", "tvmonitor"};

float confidenceThreshold = 0.2;

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

    String modelTxt = "resources/Caffe/MobileNetSSD_deploy.prototxt";
    String modelBin = "resources/Caffe/MobileNetSSD_deploy.caffemodel";

    Net net = readNetFromCaffe(modelTxt, modelBin);
    if (net.empty()) {
        std::cerr << "Can't load network by using the following files: " << std::endl;
        std::cerr << "prototxt:   " << modelTxt << std::endl;
        std::cerr << "caffemodel: " << modelBin << std::endl;
        exit(-1);
    }

    HWND hwndDesktop = GetDesktopWindow();
    //    namedWindow("output", WINDOW_NORMAL);     // Zeby mozna bylo zmieniac rozmiar okna "real-time"
    int key = 0;

    //    while( key != 27 ) {
    Mat frame = hwnd2mat(hwndDesktop);
    //        resize(frame, frame, Size(800, 450));


    //      Mat frame = imread("resources/auto.png");

    Mat img2;
    resize(frame, img2, Size(300,300));

    Mat inputBlob = blobFromImage(img2, 0.007843, Size(300,300), Scalar(127.5, 127.5, 127.5), false);

    net.setInput(inputBlob, "data");

    Mat detection = net.forward("detection_out");
    Mat detectionMat(detection.size[2], detection.size[3], CV_32F, detection.ptr<float>());

    ostringstream ss;
    for (int i = 0; i < detectionMat.rows; i++) {

        float confidence = detectionMat.at<float>(i, 2);
        if (confidence > confidenceThreshold) {
            int idx = static_cast<int>(detectionMat.at<float>(i, 1));
            int xLeftBottom = static_cast<int>(detectionMat.at<float>(i, 3) * frame.cols);
            int yLeftBottom = static_cast<int>(detectionMat.at<float>(i, 4) * frame.rows);
            int xRightTop = static_cast<int>(detectionMat.at<float>(i, 5) * frame.cols);
            int yRightTop = static_cast<int>(detectionMat.at<float>(i, 6) * frame.rows);

            Rect object((int)xLeftBottom, (int)yLeftBottom,
                        (int)(xRightTop - xLeftBottom),
                        (int)(yRightTop - yLeftBottom));

            rectangle(frame, object, Scalar(0, 255, 0), 2);

            cout << CLASSES[idx] << ": " << confidence << endl;

            ss.str("");
            ss << confidence;
            String conf(ss.str());
            String label = CLASSES[idx] + ": " + conf;
            int baseLine = 0;
            Size labelSize = getTextSize(label, FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
            putText(frame, label, Point(xLeftBottom, yLeftBottom-10),
                    FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0,255,0));
        }
    }



    imshow("output", frame);
//        key = waitKey(60);
    waitKey();
//    }

}

当我使用 exteranl 图像时，一切正常，但是当我使用名为 hwnd2mat 的函数时，它会抛出异常:

Error: Assertion failed (inputs[0]->size[1] % blobs[0].size[1] == 0) in forward

不知道是什么意思。我尝试调整图像大小，但它不起作用。

我正在使用 OpenCV-3.4.1 和 MobileNetSSD 模型。 提前致谢。

Answer 1

好吧，我终于做到了! 截图代码:

Mat getScreenshot() {
    HWND hwnd = GetDesktopWindow();
    HDC hwindowDC,hwindowCompatibleDC;

    int height,width,srcheight,srcwidth;
    HBITMAP hbwindow;
    Mat src;
    BITMAPINFOHEADER  bi;

    hwindowDC=GetDC(hwnd);
    hwindowCompatibleDC=CreateCompatibleDC(hwindowDC);
    SetStretchBltMode(hwindowCompatibleDC,COLORONCOLOR);

    RECT windowsize;    // get the height and width of the screen
    GetClientRect(hwnd, &windowsize);

    srcheight = windowsize.bottom;
    srcwidth = windowsize.right;
    height = windowsize.bottom/1;  //change this to whatever size you want to resize to
    width = windowsize.right/1;

    src.create(height,width,CV_8UC3);     // This was problem

   // create a bitmap
   int iBits = GetDeviceCaps(hwindowDC, BITSPIXEL) * GetDeviceCaps(hwindowDC, PLANES);
    WORD wBitCount;
    if (iBits <= 1)
        wBitCount = 1;
    else if (iBits <= 4)
        wBitCount = 4;
    else if (iBits <= 8)
        wBitCount = 8;
    else
        wBitCount = 24;
    hbwindow = CreateCompatibleBitmap( hwindowDC, width, height);
    bi.biSize = sizeof(BITMAPINFOHEADER);    //http://msdn.microsoft.com/en-us/library/windows/window/dd183402%28v=vs.85%29.aspx
    bi.biWidth = width;
    bi.biHeight = -height;  //this is the line that makes it draw upside down or not
    bi.biPlanes = 1;
    bi.biBitCount = wBitCount;
    bi.biCompression = BI_RGB;
    bi.biSizeImage = 0;
    bi.biXPelsPerMeter = 0;
    bi.biYPelsPerMeter = 0;
    bi.biClrUsed = 256;
    bi.biClrImportant = 0;



    // use the previously created device context with the bitmap
    SelectObject(hwindowCompatibleDC, hbwindow);
    // copy from the window device context to the bitmap device context
    StretchBlt( hwindowCompatibleDC, 0,0, width, height, hwindowDC, 0, 0,srcwidth,srcheight, SRCCOPY); //change SRCCOPY to NOTSRCCOPY for wacky colors !
    GetDIBits(hwindowCompatibleDC,hbwindow,0,height,src.data,(BITMAPINFO *)&bi,DIB_RGB_COLORS);  //copy from hwindowCompatibleDC to hbwindow


    // avoid memory leak
    DeleteObject (hbwindow);
    DeleteDC(hwindowCompatibleDC);
    ReleaseDC(hwnd, hwindowDC);

    return src;
}