Update app.py

app.py

@@ -323,6 +323,8 @@ def select_frame(v, evt: gr.SelectData):
     if evt.index != frame_selected:
         masks[frame_selected] = v
         frame_selected = evt.index
+
+    masks[frame_selected] = masks[frame_selected] - (masks[len(masks)-1]-127)
         
     return masks[frame_selected], frame_selected
 
@@ -341,7 +343,7 @@ def draw_mask(v, d, evt: gr.EventData):
     vv = json.loads(v)
     pts = np.array(vv, np.int32)
     pts = pts.reshape((-1,1,2))
-    
+
     d["layers"][0] = cv2.fillPoly(d["layers"][0], [pts], (0,0,0,255))
     d["composite"] = cv2.fillPoly(d["composite"], [pts], (0,0,0,255))