Upload onnx_inference.py

Fix the bug about no object detected.

onnx_inference.py

@@ -141,7 +141,10 @@ if __name__ == '__main__':
     det = pred[0]
     im0 = img0.copy()
 
-    if len(det):
+    if det is None:
+        print('No objects detected!')
+
+    elif len(det):
         # Rescale boxes from imgsz to im0 size
         det[:, :4] = scale_coords(img.shape[2:], det[:, :4], im0.shape).round()
 
@@ -150,5 +153,5 @@ if __name__ == '__main__':
             label = '%s %.2f' % (names[int(cls)], conf)
             plot_one_box(xyxy, im0, label=label, color=colors[int(cls)])
 
-    # Stream results
-    cv2.imwrite(new_path, im0)
+        # Stream results
+        cv2.imwrite(new_path, im0)