Do TV channels use DVD's to broadcast movies?

I'm asking because some older foreign films that I have seen in the past are grainy. But then I've noticed that lately some of these movies (Seventh Seal) are broadcast and they look so much better. Are they using the new Criterian DVD's?

Some movies on TCM look so much better now than they did several years ago. Is this due to the newly restored DVD's? Or is it because digital cable tv improves the looks?

I suppose I should know all this but I don't. Do any of you know?