void cvExtractSURF(CvArr* img, CvArr* mask, CvSeq** keypoints, CvSeq** descriptors, CvMemStorage* storage, CvSURFParams params) {
    void *fptr;

    fptr = dlsym(_Chcv_handle, "cvExtractSURF_chdl");
    if(fptr == NULL) {
        fprintf(_stderr, "Error: %s(): dlsym(): %s\n", __func__,  dlerror());
        return;
    }
    dlrunfun(fptr, NULL, cvExtractSURF, img, mask, keypoints, descriptors, storage, params);
}
