def top_down_affine(input_size: dict, bbox_scale: dict, bbox_center: dict,
                    img: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
    """Get the bbox image as the model input by affine transform.

    Args:
        input_size (dict): The input size of the model.
        bbox_scale (dict): The bbox scale of the img.
        bbox_center (dict): The bbox center of the img.
        img (np.ndarray): The original image.

    Returns:
        tuple: A tuple containing center and scale.
        - np.ndarray[float32]: img after affine transform.
        - np.ndarray[float32]: bbox scale after affine transform.
    """
    w, h = input_size
    warp_size = (int(w), int(h))

    # reshape bbox to fixed aspect ratio
    bbox_scale = _fix_aspect_ratio(bbox_scale, aspect_ratio=w / h)

    # get the affine matrix
    center = bbox_center
    scale = bbox_scale
    rot = 0
    warp_mat = get_warp_matrix(center, scale, rot, output_size=(w, h))

    # do affine transform
    img = cv2.warpAffine(img, warp_mat, warp_size, flags=cv2.INTER_LINEAR)

    return img, bbox_scale
Get the bbox image as the model input by affine transform.

    Args:
        input_size (dict): The input size of the model.
        bbox_scale (dict): The bbox scale of the img.
        bbox_center (dict): The bbox center of the img.
        img (np.ndarray): The original image.

    Returns:
        tuple: A tuple containing center and scale.
        - np.ndarray[float32]: img after affine transform.
        - np.ndarray[float32]: bbox scale after affine transform.
    
mmpose/projects/rtmpose/examples/onnxruntime/main.py