[Photo by Wang Kaihao/China Daily]

"Frescoes in Drepung Temple compose a pivotal position in studies of development of Tibetan Buddhism fine arts," Guo Hong, a researcher from the academy who has led the restoration since 2012, said.

"They offer abundant references to study Tibetan history and society."

"We were hesitant whether to repair the frescoes left by ancestors at the very beginning," Ngakwang Chozen, a high-ranking lama and deputy head of the administration committee of Drepung Monastery, said.

"However, these frescoes with Buddhist deities have crucial positions in pilgrims' hearts," he added. "If they are not in good conditions, people will be sad. So, it's better to make them bright again."