Update app.py

app.py

@@ -147,11 +147,13 @@ Try our system by uploading an image and adding your watermark below!
                detect_btn.click(
                     fn=self.detect_watermark,
                     inputs=[detect_image],
+                    outputs=detect_result
+               )
 
-    def launch(self, *args, **kwargs):
-        """Launch the interface"""
-        self.interface.launch(*args, **kwargs)
+     def launch(self, *args, **kwargs):
+          """Launch the interface"""
+          self.interface.launch(*args, **kwargs)
 
 if __name__ == "__main__":
-    app = WatermarkGUI()
-    app.launch()                            
+     app = WatermarkGUI()
+     app.launch()