Reuse code in blob.py to fix inconsistent sizes in FPN's sum

Author: daquexian

tools/convert_pkl_to_pb.py

@@ -52,6 +52,7 @@
 import utils.vis as vis_utils
 import utils.logging
 import utils.model_convert_utils as mutils
+import utils.blob as blob_utils
 from utils.model_convert_utils import op_filter, convert_op_in_proto
 
 c2_utils.import_contrib_ops()
@@ -480,10 +481,8 @@ def _prepare_blobs(
     im = cv2.resize(im, None, None, fx=im_scale, fy=im_scale,
                     interpolation=cv2.INTER_LINEAR)
 
-    blob = np.zeros([1, im.shape[0], im.shape[1], 3], dtype=np.float32)
-    blob[0, :, :, :] = im
-    channel_swap = (0, 3, 1, 2)  # swap channel to (k, c, h, w)
-    blob = blob.transpose(channel_swap)
+    # Reuse code in blob_utils and fit FPN
+    blob = blob_utils.im_list_to_blob([im])
 
     blobs = {}
     blobs['data'] = blob