It depends what you want to say. If you're looking for the pronoun corresponding to it, the correct object pronoun would be la :

Je vois une image.

Vous la voyez aussi = You can see it too

Il ne la voit pas = He can't see it

The pronoun en means 'some' or any'

Vous en voyez aussi = You can see some too

Il n'en voit pas = He can't see any

This is perfectly correct! Well done ;)