Many of them feel uncomfortable in front of the lens, so the volunteers have learned to guide their subjects, helping them adjust their expressions to capture the perfect shots.

From hundreds of shots, they carefully select the two that best portray the couple's happiness with and love for one another.

"For many of these people, the photos are their first good portraits, and may even be their last," Yu said.

For the volunteers and couples, the project has been heartwarming and fulfilling.

Yu said a grandmother once called him. She wept as she told him her husband had died, and that the photos the volunteers took were now essential mementos.

"I realized then that what we're doing is just a small act, but for some elderly people, it's very valuable work," Yu said.

He added that each year brings touching moments, but also regrets. There have been cases where couples planned to have their photos taken, but one of them died before the day assigned for the shoot.