Question

我正在尝试比较视频Feed中的连续帧。在每一帧，我都会做以下检查：

bool
DMSUSBVideoDevicePlugin::_hasImageChanged()
{
    using namespace cv;
    Mat src = cv::Mat(_captureHeight, _captureWidth, CV_8UC3, (void*) _imageData);
    /// Separate the image in 3 places ( B, G and R )
    vector<Mat> bgr_planes;
    split( src, bgr_planes );

    /// Establish the number of bins
    int histSize = 256;

    /// Set the ranges ( for B,G,R) )
    float range[] = { 0, 256 };
    const float* histRange = { range };

    bool uniform = true; 
    bool accumulate = false;

    Mat g_hist;

    /// Compute the histograms:
    calcHist(&bgr_planes[1], 1, 0, Mat(), g_hist, 1, &histSize, &histRange, uniform, accumulate);

    // Draw the histograms for Green channel alone since we know that that's where all the action is
    int hist_w = 512; int hist_h = 400;
    int bin_w = cvRound( (double) hist_w/histSize );
    Mat histImage( hist_h, hist_w, CV_8UC3, Scalar( 0,0,0) );

    normalize(g_hist, g_hist, 0.0, histImage.rows, 32, -1, Mat());

    static bool isFirstFrame = true;
    if(isFirstFrame)
    {
        _lastGreenHistogram = g_hist;
        isFirstFrame = false;
        return true;
    }

    double diff = compareHist(g_hist, _lastGreenHistogram, CV_COMP_BHATTACHARYYA);
    _lastGreenHistogram = g_hist;
    std::cout << "Diff val: " << diff << std::endl;
    if(diff > 1.f)
    {
        return true;
    }

    return false;
}

即使视频内容发生剧烈变化，从当前帧获得的直方图值也没有变化，即从前一个帧获得的viz-a-viz（基本上，diff值总是静态的）。

以下是我用不同方法得到的值：

CV_COMP_CORREL  0 
CV_COMP_CHISQR  1
CV_COMP_INTERSECT 400
CV_COMP_BHATTACHARYYA   0

有人可以帮我指出我做错了吗？

从compareHist获取不变的值

0 个答案: