CvMat* cvGetPerspectiveTransform(CvPoint2D32f* src, CvPoint2D32f* dst, CvMat* map_matrix) {
    void *fptr;
    CvMat*retval;

    fptr = dlsym(_Chcv_handle, "cvGetPerspectiveTransform_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return NULL;
    }
    dlrunfun(fptr, &retval, cvGetPerspectiveTransform, src, dst, map_matrix);
    return retval;
}
