ref_within_region(const ImageRef *ref, index_type margin_top, index_type margin_bottom) {
    return ref->start_row >= (int32_t)margin_top && ref->start_row + ref->effective_num_rows <= margin_bottom;
}
ref_within_region(const ImageRef *ref, index_type margin_top, index_type margin_bottom) {
    return ref->start_row >= (int32_t)margin_top && ref->start_row + ref->effective_num_rows <= margin_bottom;
}