Photos that capture and reveal 'unforgettable' wonders

One picture, they say, is worth 1,000 words.

Then how does one begin to describe the work of 168 photographers from around the world using their lenses to capture the beauty, natural wonders, sportsmanship and the lives of everyday people for an exhibition of 398 selected works?

Unveiled on Saturday, the 4th San Francisco International Photography Exhibition kicked off with an opening ceremony that drew attendees from near and far.

The organizer, Dong Xudong, said it took him and his photographers alliance seven months to orchestrate, plan and execute the event.

"The panels were impressed by not only the quantity but also the quality of works submitted," Dong said. "As a judge, I found it very difficult to filter out the pictures and pick the prize winners."