With a flick of his brush, Ghanaian painter Daniel Anum Jasper armed actor Paul Newman with a pair of revolvers. Unfinished paintings of a bell-bottomed John Travolta and nunchuck-spinning Bruce Lee adorned the walls of his crammed Accra studio.

Jasper, a veteran movie poster designer, was finishing up one of the 1969 classic "Butch Cassidy and the Sundance Kid," commissioned by a foreign collector who had reached out over Instagram.

From the late 1970s to the 1990s, Ghana developed a tradition of advertising films with vibrant hand-painted posters. Local cinemas were flourishing in the West African country, and artists competed over who could entice the largest audience with their often gory, imaginative and eye-popping displays.

Jasper was a pioneer of the tradition and has been painting movie posters on repurposed flour sacks for the last 30 years. But the market for his work, which once had people clamoring for theater seats, has changed.

"People are no longer interested in going out to watch a movie when it can be watched from the comfort of their phones," Jasper said.

"But there is a growing interest in owning these hand-painted posters internationally," he added. "Now they hang them in private rooms or show them in exhibitions."

With the rise of the internet, Ghana's independent cinemas fell into obscurity. But Jasper's work has gained appeal abroad, including in the United States, where the posters are valued as unique representations of a specific period in African art.

Western action flicks were mainstays of the tradition, as were Bollywood films and Chinese pictures. Many of the posters include paranormal elements and gratuitous violence even if the films had none, and physical features are wildly exaggerated.

Joseph Oduro-Frimpong, a professor in pop culture anthropology at Ghana's Ashesi University, has several of Jasper's paintings. He has collected the posters for years and has been known to buy up a closing video store's entire supply.

He plans to display his posters at the Centre for African Popular Culture opening at the university later this year, and said he hopes people appreciate their historical significance.

"Of course there is an esthetic value to the posters, how crazy it is and all of that, but we use them to have a conversation with students," he said.

"We tell them not to think about what they're seeing now... [but] to think of these art forms as symbols of history that can tell their own stories."