OpenCV直方图匹配不正确的输出

Question

I used two histograms . There have different data values in two vectors .I used opencv histogram matching functions . But it returns incorrect value. (I used CV_COMP_CORREL but I'm receiving 1 . (that value for a perfect match.) I have no idea where I have mistaken. For your reference I have attached the code below. Thank you.

histo 1code :

Mat hitograme_one()
{
    vector<double>direction_vector_test;
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(10.2);
    cv::Mat dummy_query = cv::Mat(4, 4, CV_32F, &direction_vector_test.front());
    Mat b_hist;
    float range[] = { 0, 151 };
    const float* histRange = { range };
    /// Establish the number of bins
    int histSize = 16;   // *IMPORATANT
    bool uniform = true; bool accumulate = false;
    int hist_w = 512; int hist_h = 400;
    int bin_w = cvRound((double)hist_w / histSize);

    calcHist(&dummy_query, 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate);

    return b_hist;
}

histo 2 code:

Mat histo_two()
{
    vector<double>direction_vector_test;
    direction_vector_test.push_back(20.2);
    direction_vector_test.push_back(20.2);
    direction_vector_test.push_back(20.2);
    direction_vector_test.push_back(10.2);
    direction_vector_test.push_back(40.2);
    direction_vector_test.push_back(40.2);
    direction_vector_test.push_back(40.2);
    direction_vector_test.push_back(77.2);
    direction_vector_test.push_back(88.2);
    direction_vector_test.push_back(99.2);
    direction_vector_test.push_back(100.2);
    direction_vector_test.push_back(100.2);
    direction_vector_test.push_back(100.2);
    direction_vector_test.push_back(100.2);
    direction_vector_test.push_back(100.2);
    direction_vector_test.push_back(100.2);
    cv::Mat dummy_query = cv::Mat(4, 4, CV_32F, &direction_vector_test.front());
    Mat b_hist;
    float range[] = { 0, 151 };
    const float* histRange = { range };
    /// Establish the number of bins
    int histSize = 16;   // *IMPORATANT
    bool uniform = true; bool accumulate = false;
    int hist_w = 512; int hist_h = 400;
    int bin_w = cvRound((double)hist_w / histSize);

    calcHist(&dummy_query, 1, 0, Mat(), b_hist, 1, &histSize, &histRange, uniform, accumulate);
    return b_hist;

}

Main function code: ((which returns 1 which is incorrect))

int main(int, char** argv)
{
        double compare = compareHist(hitograme_one(), histo_two(), CV_COMP_CORREL);
        cout << compare; // returns 1 which is incorrect since input vectors //have different values
        system("pause");
    return 0;
}

Answer 1

Your problem is CV_32F

cv::Mat dummy_query = cv::Mat(4, 4, CV_32F, &direction_vector_test.front());

Need to change CV_8UC1

cv::Mat dummy_query = cv::Mat(4, 4, CV_8UC1, &direction_vector_test.front());

CV_8U is unsigned 8bit/pixel - ie a pixel can have values 0-255, CV_32F is flat - the pixel can have any value between 0-1.0 so you're histogram range is populating to range from 0-1.0. Then two histogram images would be the same. So which returns the matching parameter.