[YOLOv5] Data enhancement Mosaic, turning Mosaic3 into Mosaic9

Mosaic data augmentation

Mosaic data enhancement, random cropping of pictures, zooming and arranging them into one picture, enriching data sets, adding small sample targets, and improving network training speed.

Turn Mosaic3 into Mosaic9

The data augmentation code is found in utils/dataloaders.py

mosaic = self.mosaic and random.random() < hyp['mosaic']
if mosaic:
	# Load mosaic
	img, labels = load_mosaic(self, index)  # use load_mosaic4
	
	shapes = None
	
	# MixUp augmentation
	if random.random() < hyp['mixup']:
	    img, labels = mixup(img, labels, *load_mosaic(self, random.randint(0, self.n - 1)))
	  

Put one of these:

img, labels = load_mosaic(self, index)

Change to:

img, labels = load_mosaic9(self, index)   

Then:

 img, labels = mixup(img, labels, *load_mosaic(self, random.randint(0, self.n - 1)))

Change to:

 img, labels = mixup(img, labels, *load_mosaic9(self, random.randint(0, self.n - 1)))

Change these two places, you can change Mosaic to Mosaic9