Update app.py

app.py

@@ -1120,7 +1120,7 @@ with gr.Blocks(
         )
 
         # Slider changes update viability in real-time
-        blue_threshold3.change(
+        blue_threshold4.change(
             fn=update_viability_realtime,
             inputs=[blue_threshold4, masks_state, image_state],
             outputs=[viability_overlay4, live_count_output4, dead_count_output4, viability_percent_output4, viability_info4]