The 85-year-old is probably best known for his 1967 image of a girl, Jane Rose Kasmir, holding a flower in her hand and standing in front of a row of soldiers whose rifles are raised during a U.S. demonstration against the war in Vietnam.
Describing himself as a shy character, Riboud said that in his youth he often sought solace from a noisy household and six siblings by going out alone to take photographs.
He also got a taste for adventure and independence while fighting with the French resistance during World War Two, which would serve him well over decades of travel across Asia, the Middle East, Africa and Europe.
"What comes out of those experiences is my ... independence," Riboud told Reuters by telephone.
"Even when I was at (photo cooperative) Magnum, I refused an assignment, a very important one, because it was for the National Geographic and I thought they were too rigid and professional. Magnum thought I was crazy," he added, speaking in English.
Riboud started taking pictures with his father's Kodak camera as a teen-ager, but until his mid-20s studied engineering.
He met Henri Cartier-Bresson and Robert Capa, the founders of Magnum, joined the agency in 1953 and remained there for almost three decades, taking on senior positions along the way.
Riboud believes instinct, and a "predisposition" for photography are key, and insists that when he started out "I had no idea about technique and don't even now."
His overseas assignments included a stint in London where he was sent by Capa "to see the girls and learn English" and in India and China where he traveled between 1955 and 1957.
He reported from North and South Vietnam in 1968 and 1969 during the conflict, covered the Soviet Union in 1960 and Algeria's fight for independence from France.
Riboud said he always tried to tell both sides of a story, as he did in Vietnam. In recent conflicts involving U.S. forces, many journalists have been "embedded" with troops, raising questions about the independence of their coverage.
"You have to turn and look at the egg from both sides," he said. "This is true for a country or a small town -- to see the opposite sides. That's how it was in North and South Vietnam; I was in Israel and Arab countries and very deeply independent."
"And I didn't look for scoops, I didn't know the word for scoop. I got the idea that if you look for something you miss it. You have to follow your instinct."
Riboud said he continued to travel and photograph, albeit at a less hectic pace than 30 years ago, and was working on his archive.
He will receive the prize at the Sony World Photography Awards ceremony in Cannes, southern France, on April 16.
(Editing by Paul Casciato)
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