Key art maestro Paul Crifo remembers the days of the real “Mad Men,” but it was at the Monroe Greenthal Agency where Crifo helped transform the way movies were pitched to the public.

“A lot of the agencies looked down on movie advertising. It wasn’t until later that they found how fascinating and lucrative it could be,” recalls Crifo, who worked on more than 400 campaigns during his 36-year career, the gems of which the Motion Picture Academy will feature in its Grand Lobby beginning Sept. 16.

In the early days of Hollywood, the studios developed most of their posters and newspaper ads inhouse. By mid-century, however, they started to contract the work out to New York agencies, who brought a different aesthetic. In place of carnival-style one-sheets, with their garish images and clashing fonts, movie posters began to reflect the elegant, pared-down style embraced by the guys pushing airlines and automobiles over on Madison Ave.

A believer in minimalism, white space and grid-based design, Crifo often relied on a single strong photograph (say, Gene Hackman shooting a fleeing criminal in the back for “The French Connection”) or illustration (a bed lined with ladies’ shoes for “Tom Jones”).

He would prepare dozens of mock ads for each film, collaborating with top illustrators such as Saul Bass, Mitchell Hooks, Bob McGinnis, Frank McCarthy and Bob Peak. In some cases, the client would respond to one of Crifo’s rough comps and make that the poster, as UA honcho Fred Goldberg did when he saw a design for “In the Heat of the Night” Crifo had prepared with markers and spray fixative.

To Crifo’s chagrin, since his retirement, poster design has gone the way of floating heads and Photoshop (though exceptions, such as Focus Features’ “Burn After Reading” campaign, pay homage to his hand-rendered text treatment for “The Comedians”).

“What I admire is the individual, someone who could do it all graphically with a pencil, chalk, paint, cutouts, glass, whatever,” he says. “Today, you’re stuck in the computer.”