!2348 fix image.CenterCrop.

Merge pull request !2348 from liuxiao/central_crop

mindspore/nn/layer/image.py

@@ -267,11 +267,9 @@ class PSNR(Cell):
 
 
 @constexpr
-def _check_input_3d_or_4d(input_shape, param_name, func_name):
-    """check input 3d or 4d"""
-    if len(input_shape) != 3 and len(input_shape) != 4:
-        raise ValueError(f"{func_name} {param_name} should be 3d or 4d, but got shape {input_shape}")
-    return True
+def _raise_dims_rank_error(input_shape, param_name, func_name):
+    """raise error if input is not 3d or 4d"""
+    raise ValueError(f"{func_name} {param_name} should be 3d or 4d, but got shape {input_shape}")
 
 @constexpr
 def _get_bbox(rank, shape, central_fraction):
@@ -281,6 +279,7 @@ def _get_bbox(rank, shape, central_fraction):
     else:
         n, c, h, w = shape
 
+    central_fraction = central_fraction.asnumpy()[0]
     bbox_h_start = int((float(h) - float(h) * central_fraction) / 2)
     bbox_w_start = int((float(w) - float(w) * central_fraction) / 2)
     bbox_h_size = h - bbox_h_start * 2
@@ -319,16 +318,18 @@ class CentralCrop(Cell):
         validator.check_value_type("central_fraction", central_fraction, [float], self.cls_name)
         self.central_fraction = validator.check_number_range('central_fraction', central_fraction,
                                                              0.0, 1.0, Rel.INC_RIGHT, self.cls_name)
+        self.central_fraction_tensor = Tensor(np.array([central_fraction]).astype(np.float64))
         self.slice = P.Slice()
 
     def construct(self, image):
         image_shape = F.shape(image)
         rank = len(image_shape)
-        _check_input_3d_or_4d(image_shape, "image", self.cls_name)
+        if not rank in (3, 4):
+            return _raise_dims_rank_error(image_shape, "image", self.cls_name)
         if self.central_fraction == 1.0:
             return image
 
-        bbox_begin, bbox_size = _get_bbox(rank, image_shape, self.central_fraction)
+        bbox_begin, bbox_size = _get_bbox(rank, image_shape, self.central_fraction_tensor)
         image = self.slice(image, bbox_begin, bbox_size)
 
         return image