Revision history [back]

in the end, if you need to keep your double data, you cannot use compareHist(), have to forsake all opencv optimization, and roll your own:

double BHATTACHARYYA(const Mat &h1, const Mat &h2) {
    CV_Assert(h1.type() == h2.type() == CV_64F);
    double result = 0;
    double s1=0, s2=0;
    for (int j=0; j<h1.rows; j++) {
        double a = h1.at<double>(j);
        double b = h2.at<double>(j);
        result += std::sqrt(a*b);
        s1 += a;
        s2 += b;
    }
    s1 *= s2;
    s1 = fabs(s1) > FLT_EPSILON ? 1./std::sqrt(s1) : 1.;
    result = std::sqrt(std::max(1. - result*s1, 0.));
    return result;
}