Canadian photographer Yousuf Karsh -- most famous for his iconic portrait of Winston Churchill -- is the subject of a new authorized biography that recounts how he managed to capture the British prime minister's glowering expression.

"Portrait in Light and Shadow: The Life of Yousuf Karsh," by Dr. Maria Tippett, tells the full story of how the Armenian immigrant came to Canada in the 1920, eventually becoming the most prominent portrait photographer of the twentieth century.

Karsh, who died in 2002, immortalized generations of world leaders, royalty, actors, scientists and authors through his camera lens.

Tippett's book is illustrated throughout with pictures of Queen Elizabeth II, Albert Einstein, George Bernard Shaw, Humphrey Bogart, Elizabeth Taylor, Joan Crawford, Ernest Hemingway, Pope Pius XII, Nikita Khrushchev, John F. and Jacqueline Kennedy, Pablo Picasso and Pierre Elliott Trudeau.

But it was how Karsh captured the iconic photo of British Prime Minister Winston Churchill that made him the stuff of legend.

On Dec. 30, 1941, Churchill visited Canada to speak to Parliament and had agreed to sit for a portrait with Karsh.

But Churchill, in a grumpy mood, only gave him two minutes and wanted to keep his cigar in his mouth.

"Karsh said I don't want to take another one of those damn cigar portraits," Tippett told CTV's Canada AM.

"When Churchill wouldn't take the cigar out of his mouth, Karsh did it for him and he (Churchill) scowled at him and there was that wonderful image to match the rhetoric of Churchill himself."

Karsh also photographed Bill and Hillary Clinton but was never happy with the result.

"At the beginning of that shoot, which was done in the Oval Office, Clinton came in and was rather gruff with Karsh... and this put him off," said Tippett.

"Of course the irony is (that) in the Oval Office itself, Clinton has Churchill's portrait hanging there (that Karsh took)."

Karsh was born in Mardin, a city in the Ottoman Empire on Dec. 23, 1908, but left to escape the Armenian genocide. He came to Canada in 1924 to live with his uncle, a photographer, in Sherbrooke, Que.

Karsh wanted to be a doctor but couldn't afford medical school, so after a brief apprenticeship his uncle sent him to Boston to study photography under the portraitist John H. Garo.

It was in Boston's museums and galleries that Karsh refined his eye for light and shadow.

He launched his Ottawa studio in 1932, but didn't install himself into his famed digs at the Chateau Laurier until 1972.

"If he photographed you he'd know everything about you in advance, he'd have research done on you," said Tippett.

"He would do so with a mixture of flattery and being a bully and that way he could catch you slightly off-guard and this is why he got beneath the veneer of these very, very well-known figures."

The Karsh Photographic Studio closed in 1992 and in 1997 Karsh left Ottawa, along with wife Estrellita, a medical researcher, for Boston.

He was the recipient of 17 honorary degrees and the only Canadian named one of the 100 most influential people of the 20th century by the International Who's Who

Karsh died in Boston in 2002 at the age of 93.