upd: shape check

api_server.py

@@ -86,6 +86,10 @@ def predict():
     # Get pixels out of file
     image_data = Image.open(file)
 
+    # Check image shape
+    if image_data.size != (28, 28):
+        return 'Invalid image shape. Expected (28, 28), take from <demo images> folder.'
+
     # Preprocess the image
     processed_image = preprocess_image(image_data)