A photograph of a bare-chested and tattooed passer-by on Brighton seafront has won a £12,000 prize from the National Portrait Gallery.
The subject, Joe Mochan, was snapped by photographer Richard Boll, who saw him walking past his flat this summer.
Mr Boll, 29, went outside and persuaded Mr Mochan to let him take the picture, all in the space of four minutes.
The gallery whittled down 2,021 entries before choosing the recipient of its Photographic Portrait Prize.
There were three other finalists - a family in a living room photographed by New York-based Anna Bauer; a model at an educational training centre by Londoner Kiran Master; and a grandmother rehearsing for a performance by American photographer Kyoko Hamada.
The winning image was from Mr Boll's "Pavement" series, described as a collection of "very informal, quickly shot" photos of people in Brighton.
"Brighton has a diverse population, that's why I enjoy taking portraits there," he said.
Mr Boll, who was brought up on the Isle of Wight and studied at the Edinburgh College of Art, said he had developed "an obsessive-compulsive disorder" for photography.
Of his prize-winning photo, he said: "Joe immediately interested me. It was a quick encounter, three or four minutes, most of which was spent persuading him to pose.
"In Joe's portrait there are details that hint at a certain vulnerability, but these are played off against other details, like his tattoos and adornments, which suggest resilience and self-belief.
"His expression defies interpretation," Mr Boll concluded.