@theis,
Nope.
You can not visualise the person You have not seen.
Memory (which is the part of brain, in short data store house) will store the information which is collected through 5 senses, that is tangible, analyses that information and takes out particular that file from that folder from that particular drive, when you try to retrieve/recollect.
And all that is possible only then, when you have received/collected that information through your one of the sense organ, in this case which is "EYES".
So, no. you simply just can not visualise the person You have not seen.