I don't see why you'd need a dataset of 8k images in order to upsample 4k to 8k, as long as there are 4k images of that object from at least twice as close as y

I don't see why you'd need a dataset of 8k images in order to upsample 4k to 8k, as long as there are 4k images of that object from at least twice as close as you're shooting from. (Actually I think twice as close might be 16k, but you get the point...)