Mr. Hockney, with a poster for the show (Photo courtesy of Getty Images)

The posters for David Hockney's upcoming show at the Royal Academy of Arts in London, "A Bigger Picture," feature a line of copy that boasts "All the works here were made by the artist himself, personally," a swipe directed at Damien Hirst ahead of that artist's 11-gallery spot painting show at Gagosian.

Citing another interview with The Radio Times, The Independent reports that Mr. Hockney did confirm that Mr. Hirst was his target with the line on the poster. Mr. Hockney said Mr. Hirst's use of assistants in creating his work is "a little insulting to craftsmen, skillful craftsmen."

Actually, Mr. Hirst gave his assistants quite a bit of credit in a recent interview with The New York Times about the show.

One time an assistant painted five yellow spots in a row. “I told him those aren’t random,” Mr. Hirst recalled. “And we had a big fight. Now I realize he was right, and I was wrong.”

Mr. Hockney's show opens on January 21, Mr. Hirst's on the 12th.