High-tech laser technology has been used to record and conserve one of the finest collections of Pictish carved stones in Scotland.
The Pictish carved stones date from the decades before 843 AD
The St Vigeans Stones from Arbroath are being cleaned by a specialist team of Historic Scotland experts in Edinburgh.
Earlier efforts at conservation, dating back to the 1960s, carried out using the best techniques of the time have now reached the end of their life.
The project removes the earlier repairs and uses more modern treatments.
The project is part of works to upgrade St Vigeans Museum of Pictish Carved Stones in Arbroath.
It is hoped the stones will be returned by the end of this year with the new-look museum reopening in time for Easter 2009.
Fresh research into the 38 stones suggests St Vigeans was once home to an important royal monastery.
It has also cast fresh light on the religious beliefs of the Picts, to fill gaps in understanding of their culture and ideas.
Stephen Gordon, Historic Scotland senior conservator, said: "The improvements to the museum gave us an excellent opportunity to bring the stones to Edinburgh, where we have the specialist staff and equipment to undertake some thorough conservation treatment and prepare new mounts.
"This has included using special laser techniques that are superb for removing dirt, or other unwanted materials, without affecting the stones themselves.
St Vigeans Museum of Pictish Carved Stones reopens in 2009
"Earlier efforts at conservation, dating back to the 1960s, have now reached the end of their life.
"This project gives us the opportunity to remove these earlier repairs and use more modern and appropriate treatments and mounting methods."
The collection includes the Drosten Stone, a cross slab with ornate cross and fantastic beasts, plus a rare Latin and Pictish inscription which might have commemorated King Uoret who died around 842 AD.
The stones date from the decades before 843 AD when the Pictish kingdom was united with Gaelic Dalriada under a single monarch, leading to the birth of Scotland.
Peter Yeoman, Historic Scotland senior archaeologist, said: "The stones are among the last and very finest expressions of Pictish art, which makes them tremendously important.
"These large stone crosses would originally have been set up as monuments, boundary markers and gravestones on the church hill at St Vigeans.
"We have known for some time that the area was an important royal centre, but the latest thinking is that the high quality carvings, with scriptural images, indicate that there was not just a church but an important monastery under royal patronage at St Vigeans.
"It may also have been a significant pilgrimage centre, perhaps due to the presence of relics of the Irish St Fechin, from who the village took its name."