Upon its release 50 years ago today, the Beatles’ “Sgt. Pepper’s Lonely Hearts Club Band” album was hailed in some quarters as a groundbreaking milestone in popular music.

Others scoffed at it, calling it an overly ambitious effort for artistic respectability that abandoned the innocence of the group’s early hits.

In the ensuing five decades, the debate has raged on — and it is likely to gain renewed fervor with  the release Friday of the golden-anniversary edition of the album, newly remixed in stereo by Giles Martin (son of the album’s original producer, George Martin).

The project wasn't simply meant to serve up a new edition of a classic album that scads of Beatles fans are likely to lap up — even though many will.

Rather, it is an attempt to rectify what has long been perceived as a significant — though hardly fatal — flaw in the original stereo version, created with considerably less time and attention from band members Paul McCartney, John Lennon, George Harrison and Ringo Starr.

The hope is that the new iteration will introduce the work to younger audiences and sound more akin to contemporary recordings.

In late 1966, as McCartney, Lennon, Harrison and Starr set to work on “Sgt. Pepper” as the follow-up to “Revolver,” monaural sound was the dominant format for music.

Stereo counterparts often were created hastily for the United States and other foreign markets. Lennon, in fact, once stated, “You haven’t heard ‘Pepper’ until you’ve heard the mono version.”

That's partly because the group’s vocals are often divorced from the instrumental accompaniment, separated in different channels because that was how the engineers charged with creating the stereo version could get the job done quickly.

George Martin and the Beatles spent about three weeks mixing the mono version; its stereo counterpart was completed in barely two days, according to Sam Okell, Abbey Road Studios chief engineer and chief collaborator on the new edition.

“There is a thing about the mono mix,” Martin said. “There is immersion that comes from the depth they put in there, even though it is just coming out of one speaker. I was trying to create that (in stereo). No one can say the (1967) stereo mix is not a great-sounding record. But there’s a way to get the best of both worlds.”

Feedback on the new mix, he said, has been “almost humiliatingly positive."

The remix isn't the only recognition of the album's anniversary.

On Saturday night, PBS will premiere “Sgt. Pepper’s Musical Revolution,” which is hosted by composer, music historian and documentarian Howard Goodall.

“I know it’s a landmark in terms of pop culture — the Summer of Love, youth culture, the '60s,” Goodall said, “but really what I’m interested in is: What does this music say today? Why has it been treated with such respect for 50 years?”

Greg Harris, executive director of the Rock and Roll Hall of Fame and Museum in Cleveland, noted, “Stylistically they were throwing garage rock in with music hall with Indian ragas."

“Sgt. Pepper,” the most elaborate reissue yet of an individual Beatles album, is being offered in several configurations: on CD, digital and on vinyl — the last in a half-speed mastered pressing that ups the audio fidelity one more notch. It is accompanied by a second LP containing alternate mixes of all 13 “Sgt. Pepper” songs as selected by Giles Martin.

Overall, the “Sgt. Pepper” remix represents what the Beatles and George Martin might have done had they cared about stereo in 1967.

“It improves upon what was done 50 years ago while paying homage to the mono mix that the purists say is the only way to hear ‘Pepper,’" said Beatles historian Bruce Spizer, author of nearly a dozen books on the group’s recorded legacy and a new volume, “The Beatles and Sgt. Pepper: A Fans’ Perspective.” 

“Like a lot of Beatles stuff,” he said, “it’s a bit like opening up a body, in a way. And you find it’s really healthy. All of the bits and pieces that make up ‘Sgt. Pepper’s’ are there for a reason.”

Remixing one of the most hailed works in rock music called for more than myriad judgment calls on how much reverb to use, when to up the automatic double tracking, and when and where to split instruments or vocals into different channels.

“For my father,” Martin said, “it was the happiest time (working with the Beatles), I think, because they were all pulling in the same direction. In a typical Beatles way, they were actually pushing more than pulling: pushing their past away.

“They were almost deliberately not making an album for their screaming fans. That’s what was interesting.”