Pittsburgh ? Artist Shepard Fairey, who recently admitted concealing a key mistake in a lawsuit over his use of an Associated Press photo in his famous Barack Obama “HOPE” poster, said Saturday that the error should not be viewed as “premeditated and sinister.”

Fairey was at the Warhol Museum in Pittsburgh on Saturday night for the opening of an exhibit of his works — including the 4-foot-by-8-foot Obama poster. He drew a chuckle from the crowd during a question and answer session when he said, “I am learning from my mistakes, if everybody’s been keeping up with the news.”

On Friday, Fairey’s attorneys — led by Anthony Falzone, executive director of the Fair Use Project at Stanford University — said they intend to withdraw from the case and said the artist had misled them by fabricating information and destroying other material.

Fairey admitted that he didn’t use The Associated Press’ photo of Obama seated next to actor George Clooney he originally said his work was based on — which he claimed would have been covered under “fair use,” the legal claim that copyrighted work can be used without having to pay for it.

Instead he used a picture the news organization has claimed was his source — a solo picture of the future president seemingly closer to the iconic red, white and blue image of Obama, underlined with the caption “HOPE.” Fairey said that he tried to cover up his error by submitting false images and deleting others.

The distinction is critical because fair use can sometimes be determined by how much of an original image or work was altered in the creation of a new work. If Fairey didn’t need to significantly alter the image he used — in this case the solo shot of Obama — then his claim could have been undermined.

Laurence Pulgram, an intellectual property lawyer who represented Napster in a copyright fight with the rock band Metallica, said Saturday that Fairey’s case was in trouble.

“This was a brain-dead move by Mr. Fairey, and it could be the turning point. His lawyers will still be able to argue that he made a ‘fair use’ under copyright law, but it’s a whole lot less likely that the court or jury will think that what he did was actually ‘fair’ if he has lied and tried to mislead the entire world about what use he made,” Pulgram said.

Fairey said Saturday it was wrong to portray the error in his initial claim “as if it was very, very premeditated and sinister.”