Update utils.py

utils.py

@@ -306,7 +306,7 @@ class Dataset(object):
                 scores.append(score)
 
         image = self.load_image(image_id)
-        mask = np.stack(instance_masks)
+        mask = np.dstack(instance_masks)
         class_ids = np.array(class_ids, dtype=np.int32)
         scores = np.array(scores, dtype=np.float32)
         _, window, scale, padding, crop = resize_image(