These are the images [which were presented by us].
 These are the images [presented by us].
Compare the two examples. In  the bracketed element is a relative clause modifying "images".
In  the bracketed clause also modifies "images", but this time it's a past-participial clause, not a relative one. Semantically they are similar, of course, but we don't call  a relative clause since there's no possibility of inserting a relative phrase (cf. *"These are the images which presented by us".). I don’t want to be positing a deleted verb.
Some people call  a 'reduced relative clause', but that term is a misnomer. The crucial property of relative clauses is the presence of some relativised element (overt or covert) that is anaphorically linked to a noun or nominal, and this property is not present here.