Replacing dummy door knobs

[PickledWilly]

This might be a ridiculous question. We have some dummy door knobs downstairs (only two - open plan) and want to replace them for real door handles. Is this possible? What do I need to buy?

When you say they are dummy door handles, do you mean they just pull and the door opens and you want to replace them with regular handles that you push down-so the latch but goes in-to open the door?

Like this?