Mr. Fairey decided to create the image on his own before contacting the Obama campaign, which welcomed it but never officially adopted it because of copyright concerns. Before the election, Mr. Fairey was best known for his fake-advertising stickers and posters, pasted in cities across the country, showing an ominous, abstracted image of the wrestler Andre the Giant along with the word “Obey.”

Mr. Fairey is the focus of a retrospective that opened last week at the Institute of Contemporary Art in Boston. (In a development that was not much of a surprise, he was arrested there on Friday, accused of illegally pasting his work in places around Boston; he has pleaded not guilty.) A collaged work made by Mr. Fairey based on his Obama poster was acquired last month by the National Portrait Gallery in Washington, part of the Smithsonian Institution, and placed in its permanent collection.

After Mr. Obama’s victory, speculation increased about which picture had served as the basis for Mr. Fairey’s posters. In interviews the artist said that it was one he had found on the Internet. Bloggers, including the Manhattan gallery owner James Danziger, pursued several leads until, according to the lawsuit, Tom Gralish, a Pulitzer Prize-winning photographer for The Philadelphia Inquirer, helped track down a photo by Mr. Garcia that showed Mr. Obama sitting beside the actor George Clooney at a 2006 event about Darfur at the National Press Club.

Further complicating the dispute, Mr. Garcia contends that he, not The Associated Press, owns the copyright for the photo, according to his contract with the The A.P. at the time. In a telephone interview on Monday, Mr. Garcia said he was unsure how he would proceed now that the matter had landed in court. But he said he was very happy when he found out that his photo was the source of the poster image and that he still is.

“I don’t condone people taking things, just because they can, off the Internet,” Mr. Garcia said. “But in this case I think it’s a very unique situation.”

He added, “If you put all the legal stuff away, I’m so proud of the photograph and that Fairey did what he did artistically with it, and the effect it’s had.”