Proceedings of the Society of Antiquaries of Scotland

This journal is a good source for archaeological and historical works relevant to studying and depicting the Picts and I have just discovered that PDFs of Vols. 1 (1852) to 102 (2002) are available online here: http://ads.ahds.ac.uk/cfm/archway/volumeSelector.cfm?rcn=1340

Some examples of the breadth of imagery of the Picts: contemporary; historical and modern ...

How the Picts depicted themselves:

A stone slab from Bullion, Invergowrie, Angus, Scotland (discovered in 1934) which Laing and Laing (1984) argue may date from the Eighth century CE because of the similarity of the bird's head terminal on the drinking horn to those in the Lindisfarne Gospels. (Source: Lloyd Laing and Jennifer Laing, 'Archaeological notes on some Scottish early Christian Sculptures,' Proceedings of the Society of Antiquaries of Scotland, 114 (1984), 277–287, p. 286)

Romantic images of the Picts:

Modern depictions (!):