double cvThreshold(CvArr* src, CvArr* dst, double threshold, double max_value, int threshold_type) {
    void *fptr;
    double retval;

    fptr = dlsym(_Chcv_handle, "cvThreshold_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return -1;
    }
    dlrunfun(fptr, &retval, cvThreshold, src, dst, threshold, max_value, threshold_type);
    return retval;
}
