Update app.py

app.py

@@ -27,7 +27,7 @@ def load_image(image_file):
 def convert_one_channel(img):
     #some images have 3 channels , although they are grayscale image
     if len(img.shape)>2:
-        img=img[:,:,0]
+        img= cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
         return img
     else:
         return img