(CNN) -- The process of restoring a classic film -- indeed a film considered one of the greatest in movie history -- conjures up the old joke about how to feed a hungry lion.

The answer: very carefully.

Such was the challenge to the folks at the Criterion Collection when they embarked on a project to reissue Akira Kurosawa's 1954 work "Seven Samurai." The film had been the second the company had ever released on DVD, in 1998, in an edition that duplicated a version the company had put out in the now-defunct laserdisc format.

But technology had greatly improved in the ensuing decade, and when the opportunity came to clean up a release that Criterion executive producer Kim Hendrickson describes as "substandard" by the company's lights, they dove in.

"It was a huge opportunity to tackle a great film," she said.

Not that it was easy.

"Samurai" is one of Kurosawa's masterpieces, a 207-minute epic of 16th-century Japan. Villagers, terrorized by bandits, asks an old samurai if he'll defend their town. He finds six other samurai -- as well as an apprentice -- and the group does battle with the bandits.

The simple plot doesn't do justice to the movie, which includes an energetic and almost feral performance by Toshiro Mifune and concludes with a messy, gloriously shot and edited confrontation in the rain.

"Complicated tracking shots compete with equally elaborate and fast-paced editing to create a film whose constant prevailing tempo is that of war punctuated by ever shorter intervals of peace," wrote film historian David Cook in "A History of Narrative Film," describing "Samurai" as "a stunning achievement."

The film inspired "The Magnificent Seven" (1960), along with a number of other American (and spaghetti) Westerns.

"This is a special film," said Lee Kline, the technical director on the "Samurai" reissue, which came out at the beginning of September.

But special or not, it had been more than a half-century since "Samurai" was made, and the original negative -- the source material for printing the finished product on celluloid -- was missing.

To begin the process, Criterion located an early negative and an early positive and determined the positive was the closest to the original. So the company made a new negative, using "Wetgate processing," a chemical system that fills in flaws in the original material.

That was just for starters. The technical team had to cope with the fact that the positive had shrunk, meaning that light could get in around the edges of the frame; that scenes contained black frames or missing frames, making transitions jarring; even that the original mono soundtrack had to be restored. (Click here for before-and-after versions of frame details.)

Some issues were dealt with through technology; others took painstaking research, as with a search to find existing versions of the film's shots without the black frames.

In some cases, the Criterion crew had to ask itself what the filmmaker intended. (Kurosawa died in 1998.) One scene shows a very obvious hair at the top of the frame, a hair that probably existed in Kurosawa's camera -- and has been seen in the film since its release.

"They opted not to reshoot, and we had to honor that," Kline said. The crew is constantly asking itself, he said, "When we fix something, are we doing something we shouldn't do?"

The result -- which took two years and thousands of hours -- has earned raves from cinephiles. "This is my vote for release of the year," wrote reviewer Pat Wahlquist on HomeTheaterForum.com.

Kline said he is pleased as well, though he always wishes he had more time.

"For the most part, you wish you had a few more weeks," he said. "People are used to pristine. But if we did that, we'd never get it out."