Copy-Paste augmentation for YOLOv5 (#3845)

* Copy-paste augmentation initial commit

* if any segments

* Add obscuration rejection

* Add copy_paste hyperparameter

* Update comments

data/hyps/hyp.finetune.yaml

@@ -36,3 +36,4 @@ flipud: 0.00856
 fliplr: 0.5
 mosaic: 1.0
 mixup: 0.243
+copy_paste: 0.0

data/hyps/hyp.finetune_objects365.yaml

@@ -26,3 +26,4 @@ flipud: 0.0
 fliplr: 0.5
 mosaic: 1.0
 mixup: 0.0
+copy_paste: 0.0

data/hyps/hyp.scratch-p6.yaml

@@ -31,3 +31,4 @@ flipud: 0.0  # image flip up-down (probability)
 fliplr: 0.5  # image flip left-right (probability)
 mosaic: 1.0  # image mosaic (probability)
 mixup: 0.0  # image mixup (probability)
+copy_paste: 0.0  # segment copy-paste (probability)

data/hyps/hyp.scratch.yaml

@@ -31,3 +31,4 @@ flipud: 0.0  # image flip up-down (probability)
 fliplr: 0.5  # image flip left-right (probability)
 mosaic: 1.0  # image mosaic (probability)
 mixup: 0.0  # image mixup (probability)
+copy_paste: 0.0  # segment copy-paste (probability)