yolov5 servitization optimization (#262)

* yolov5 split pre and post process

* yolov5 postprocess

* yolov5 postprocess

python/fastdeploy/vision/detection/contrib/yolov5.py

@@ -37,6 +37,31 @@ class YOLOv5(FastDeployModel):
         return self._model.predict(input_image, conf_threshold,
                                    nms_iou_threshold)
 
+    @staticmethod
+    def preprocess(input_image,
+                   size=[640, 640],
+                   padding_value=[114.0, 114.0, 114.0],
+                   is_mini_pad=False,
+                   is_no_pad=False,
+                   is_scale_up=False,
+                   stride=32,
+                   max_wh=7680.0,
+                   multi_label=True):
+        return C.vision.detection.YOLOv5.preprocess(
+            input_image, size, padding_value, is_mini_pad, is_no_pad,
+            is_scale_up, stride, max_wh, multi_label)
+
+    @staticmethod
+    def postprocess(infer_result,
+                    im_info,
+                    conf_threshold=0.25,
+                    nms_iou_threshold=0.5,
+                    multi_label=True,
+                    max_wh=7680.0):
+        return C.vision.detection.YOLOv5.postprocess(
+            infer_result, im_info, conf_threshold, nms_iou_threshold,
+            multi_label, max_wh)
+
     # 一些跟YOLOv5模型有关的属性封装
     # 多数是预处理相关，可通过修改如model.size = [1280, 1280]改变预处理时resize的大小（前提是模型支持）
     @property