Unless I missed your point I see:
1) source_citation pointing to the place, the URL on the website that has the information I am citing. for example: http://www.arkivverket.no/URN:kb_read?idx_kildeid=7353&u...
2) source_citation.media is a picture of the page I found the information on. This can be either a PDF or a jpg. Both are the same to me. for example this jpg would have a media object in the GEDCOM as a picture of the URL/page above.