What is upsampling, and why should it be used with caution?

Question

i know upsampling is increasing the resolution but not sure as to why it should be used with caution.

Answer 1

Up sampling is increasing the resolution which in turn creates data that isn't really there.

Have you ever seen analog television on a nice big high definition television?  How does it look?  Shouldn't it look better because it's on a high definition television?   It's very similar with up-sampling to get a higher resolution.  That's why it should be used with caution.  If you have a noisy image, you are sampling that noise and increasing it.