Parameterize max_det + inference default at 1000 (#3215)

* Added max_det parameters in various places

* 120 character line

* PEP8

* 120 character line

* Update inference default to 1000 instances

* Update inference default to 1000 instances

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

utils/general.py

@@ -482,7 +482,7 @@ def wh_iou(wh1, wh2):
 
 
 def non_max_suppression(prediction, conf_thres=0.25, iou_thres=0.45, classes=None, agnostic=False, multi_label=False,
-                        labels=()):
+                        labels=(), max_det=300):
     """Runs Non-Maximum Suppression (NMS) on inference results
 
     Returns:
@@ -498,7 +498,6 @@ def non_max_suppression(prediction, conf_thres=0.25, iou_thres=0.45, classes=Non
 
     # Settings
     min_wh, max_wh = 2, 4096  # (pixels) minimum and maximum box width and height
-    max_det = 300  # maximum number of detections per image
     max_nms = 30000  # maximum number of boxes into torchvision.ops.nms()
     time_limit = 10.0  # seconds to quit after
     redundant = True  # require redundant detections