图像预处理如何快速便捷的实现keep ratio操作

def get_input(img, shape_hw, keep_raito=True): import mmcv if not isinstance(img, np.ndarray): img = mmcv.imread(img) assert shape_hw[0] % 32 == 0 and shape_hw[1] % 32 == 0 if keep_raito: img, scale_factor = mmcv.imrescale(img, shape_hw, return_scale=True) img = mmcv.impad(img, shape=shape_hw, pad_val=0) else: img, w_scale, h_scale = mmcv.imresize(img, shape_hw, return_scale=True) scale_factor = np.array([w_scale, h_scale, w_scale, h_scale], dtype=np.float32) return img, scale_factor