Add confidence score to label txt files (ultralytics#994)

* add contrast to conf/class against bbox rectangle color

* added feature to save conf in txt labels

* Update general.py

* Update detect.py

* Update detect.py

* Update detect.py

save_conf variable removed as only used once, so we can use opt.save_conf instead.

* Update detect.py

* Update detect.py

Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

detect.py

@@ -104,8 +104,9 @@ def detect(save_img=False):
                 for *xyxy, conf, cls in reversed(det):
                     if save_txt:  # Write to file
                         xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist()  # normalized xywh
+                        line = (cls, conf, *xywh) if opt.save_conf else (cls, *xywh)  # label format
                         with open(txt_path + '.txt', 'a') as f:
-                            f.write(('%g ' * 5 + '\n') % (cls, *xywh))  # label format
+                            f.write(('%g ' * len(line) + '\n') % line)
 
                     if save_img or view_img:  # Add bbox to image
                         label = '%s %.2f' % (names[int(cls)], conf)
@@ -154,6 +155,7 @@ def detect(save_img=False):
     parser.add_argument('--device', default='', help='cuda device, i.e. 0 or 0,1,2,3 or cpu')
     parser.add_argument('--view-img', action='store_true', help='display results')
     parser.add_argument('--save-txt', action='store_true', help='save results to *.txt')
+    parser.add_argument('--save-conf', action='store_true', help='output confidences in --save-txt labels')
     parser.add_argument('--classes', nargs='+', type=int, help='filter by class: --class 0, or --class 0 2 3')
     parser.add_argument('--agnostic-nms', action='store_true', help='class-agnostic NMS')
     parser.add_argument('--augment', action='store_true', help='augmented inference')