Greek to English Art/Literary Printing & Publishing

The sentence in which the word occurs is:

Αριστερά, το σχήμα του σύννεφου που ενέπνευσε κάθε ποίημα, πατημένο με μολύβι.

(The narrator is describing the form that her first book of published poems took).

'πατημένο' is clearly the neuter past particple of 'πατω', but I can't see how it's being used here. 'Trampled/trodden with pencil' makes no sense to me... so I was thinking that this must be some specialised used of the word in printing or art.