fix bbox for pascal voc loading and saving

supervision/dataset/formats/pascal_voc.py

@@ -39,6 +39,16 @@ def object_to_pascal_voc(
     return root
 
 
+# Correction functions for VOC XML format as bounding boxes in VOC XML start at (1,1) not (0,0). Refer:
+# https://github.com/roboflow/supervision/issues/144
+def __increment_bbox_for_pascal_voc(xyxy):
+    return xyxy + 1
+
+
+def __decrement_bbox_for_pascal_voc(xyxy):
+    return xyxy - 1
+
+
 def detections_to_pascal_voc(
     detections: Detections,
     classes: List[str],
@@ -106,11 +116,11 @@ def detections_to_pascal_voc(
             for polygon in polygons:
                 xyxy = polygon_to_xyxy(polygon=polygon)
                 next_object = object_to_pascal_voc(
-                    xyxy=xyxy, name=name, polygon=polygon
+                    xyxy=xyxy + 1, name=name, polygon=polygon
                 )
                 annotation.append(next_object)
         else:
-            next_object = object_to_pascal_voc(xyxy=xyxy, name=name)
+            next_object = object_to_pascal_voc(xyxy=xyxy + 1, name=name)
             annotation.append(next_object)
 
     # Generate XML string
@@ -146,12 +156,14 @@ def load_pascal_voc_annotations(
 
         # Correction for VOC XML format as bounding boxes in VOC XML start at (1,1) not (0,0). Refer:
         # https://github.com/roboflow/supervision/issues/144
-        x1 = int(bbox.find("xmin").text) - 1
-        y1 = int(bbox.find("ymin").text) - 1
-        x2 = int(bbox.find("xmax").text) - 1
-        y2 = int(bbox.find("ymax").text) - 1
+        x1 = int(bbox.find("xmin").text)
+        y1 = int(bbox.find("ymin").text)
+        x2 = int(bbox.find("xmax").text)
+        y2 = int(bbox.find("ymax").text)
 
-        xyxy.append([x1, y1, x2, y2])
+        xyxy.append(
+            __decrement_bbox_for_pascal_voc(np.array([x1, y1, x2, y2])).tolist()
+        )
 
     xyxy = np.array(xyxy)
     detections = Detections(xyxy=xyxy)