@void32 the values taken into consideration for mean and std for the transforms:

Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])]) is used for the ImageNet dataset

And,

Normalize(mean=[0.5, 0.5, 0.5], std=[0.5, 0.5, 0.5])] is used to convert input image colors to gray scale
You can check Understanding transform.Normalize( ) 73 for a better insight