In this paper

we introduce our research on virtual restoration and gradual changing simulation of Dunhuang frescoes. We present a feasible restoration model as well as introduce the technologies used. The model is designed to give instructions for restoration facsimilers

fresco researchers and fresco protectors. With the assistant of computer

it is a new and more effective way than manual to protect and preserve Dunhuang fresco which is one of the most brilliant culture heritages of the world. The fresco image restoration result can even be used in virtual cave navigation system to show the brilliance of the grottoes in ancient time. Based on the pigment component research of Dunhuang experts

the experience knowledge of Dunhuang artists

and the current well preserved frescoes

we studied color knowledge

image processing

artifical intelligence and etc to restore some color changing

color fading and color stripping Dunhuang frescoes in computer. The most important of the restoration procedure is to separate the fresco image into some recovery objects(In this paper we adopt color layer division and edge detection technology). And then for each recovery object we get appropriate experience knowledge or analogical images for restoration guidance. Of course it still need some image processing tools such as cleaning dirty

color harmonize and etc to improve the last effect of the whole image. With the restored results then we can simulate the procedure that the frescoes change gradually from origin to current status. We made gradually changing demos for each category of restoration. We are satisfied with part of the results

and the achievement is shown in the EXPO'2000 in Hannover

Germany.