A screen ca pture from "Dingjun Mountain". [Photo/Agencies]

In a dark workshop in Beijing, film reels are stacked on the floor in cases that have seen better days. Their contents are waiting to be transferred to a digital format.

The China Film Archive (CFA) is working to save these old films, the treasures of a Chinese movie industry that is celebrating its 110th birthday this year. Considered the first film made in China, 1905 short "Dingjun Mountain" gave birth to a sector that is flourishing today as never before.

The reels came from Shaanxi Province's Xi'an Film Vault, a giant climate-controlled warehouse designed for careful storage of the delicate archives.

"The temperature must be kept between minus and plus 5 degrees centigrade," says CFA engineer Wang Zheng. "The indoor relative humidity must be 30 to 40 percent."

Even more complex processes are involved in the restoration project, which has been reclaiming and preserving valuable material for film historians since its launch in late 2006.

After cleaning and repairing the film with chemical reagents, Wang scans it using a telecine machine and transfers the footage to the CFA's central system.

"We use several computer programs, including Photoshop, to digitally restore the footage," Wang explains. This step is the most time-consuming as the engineers must check and patch the films frame by frame, staring at a screen for hours.

"We're all under age 40, but our heads are spinning after a day's work," Wang says.

A skillful film restorer can finish 200 frames at most in a day. A 90-minute feature -- with around 130,000 frames -- can take six months to restore.

"Old film dims and gets dirty over the years," says Wang. "We must not only repair them technically, but also keep their historical integrity."