Thanks for clarification @albanD
I used the line of code below to convert a gray-scale image to a 3-channel image so I can use my data with a pretrained model (for RGB input), without using triple the memory. I was hoping to confirm I was saving memory using view() and expand(), but I can’t find a way to explicitly measure this? Otherwise, I’ll probably just assume it’s doing what I think 
img_3_dims = img.view(img.shape + (1,)).expand(-1,-1,3)