enable eval_mode to make infer return value

app.py

@@ -70,6 +70,7 @@ def process_image(image, model_size, task_type):
             crop_mode=config["crop_mode"],
             save_results=True,
             test_compress=True,
+            eval_mode=True,
         )
 
         print(f"====\nresult: {result}\n====\n")