Question

Is it legal to download pictures from the internet?

Answer 1

Of course it is. No one's going to come and track you down for downloading an image from the internet.

In many cases, images may be under some sort of ownership license like copyright, preventing you from modifying and distributing the image as your own. But again, so many people do it anyway, because no one is going to come knocking on your door because you downloaded an image from the internet.