Art lovers would howl if a few inches were trimmed from a favorite Picasso. Readers would wail if the only available copies of ''War and Peace'' were abridgments.
But things just like this happen to moviegoers. If a film is long, or seems that way, the producer or distributor may lop off a few minutes - to ''improve'' the picture, or to squeeze in another showing per day.
There's a long history of this. In the golden age of Hollywood plenty of major works were mauled by studio moguls - the most famous being ''Greed,'' by Erich von Stroheim, which was scissored by six hours, the footage now lost forever.
Adding to the confusion, filmmakers themselves may cut a finished movie - perhaps to get a new rating, as when Stanley Kubrick changed ''A Clockwork Orange'' from X to R by snipping a few seconds. Thus some movies, like some operas, exist in different versions dating from different times. And importers have chopped many films to suit their idea of American attention spans.
Some pictures may be helped by such treatment, just as some books cry out to be shortened. And most viewers may not know, or care, about these backstage maneuvers. But film scholars do. And when they get riled up about something, happy surprises can result.
It's a growing phenomenon. Not long ago, for example, Abel Gance's epic ''Napoleon'' - drastically cut after it was made in 1927 - was restored to its four-hour length by a dedicated researcher and enjoyed a new success with general audiences. More recently, ''The Seven Samurai'' was reissued at the 31/2 hours its director, Akira Kurosawa, always intended.
Now two more restorations have arrived, as different as can be. ''A Star Is Born'' is vintage Hollywood, bigger and brassier than ever in its new edition, which runs more than three hours. ''The Leopard'' is an imposing feat of European romanticism, now with its original Italian sound track and 24 minutes of footage that was cut when the film was first released to the United States in the mid-1960s.
A Star Is Born was directed by George Cukor from a screenplay by Moss Hart, with Harold Arlen music and Ira Gershwin lyrics. It bowed in 1954, in a reserved-seat ''road show'' engagement. The running time was about three hours - and sure enough, exhibitors were nervous because this limited the number of screenings possible each day.
According to a report on the movie's history supplied by Warner Bros., it was Jack Warner himself who bowed to the pressure, splicing together a condensed version. Not only the release prints, but even the studio's master negative were trimmed, and much of the discarded material was melted down (standard practice in past years) to reclaim its silver content.
The truncated movie then went to neighborhood theaters everywhere. And for nearly 30 years, unmindful of the missing 30 minutes, audiences thrilled to the drama of Esther Blodgett, the rising young star, and Norman Maine, the sadly besotted matinee idol who becomes her mentor and husband.
It was Ron Haver, head of the Los Angeles County Museum of Art film department, who had the bright idea of searching for the supposedly lost portions. After a difficult search, he ferreted out some 20 minutes of footage from the Warner vaults and located the original three-hour sound track. Pictures and sound were then synchronized and combined, with still photos filling a few gaps.
The restored film was the main attraction at a series of benefit screenings presented last July by the Academy of Motion Picture Arts and Sciences, the Academy Foundation, and some other institutions, in cooperation with Warner Bros. - all to raise money for a film-restoration program called the ''Decade of Preservation.'' Now the reborn ''Star'' has gone into general release, in a version that's five minutes longer yet, the original negative of one production number (called ''Lose That Long Face'') having been dug up and added to the rest.
That's the news; now for the review. Is the restored ''Star'' really worth all the fuss that went into it? Yes and no. It's a good movie, but not a great one, and 185 minutes seems a long time to dwell on its now-familiar story. Cukor's vision of the tale was certainly expansive. It wasn't always dynamic,
though, and the full-length version has its share of sleepy moments. Even the legendary Judy Garland (the movie was conceived as a comeback vehicle for her) doesn't always have enough tricks up her sleeve to sustain a too-long sequence. And when the logic or psychology of the tale seems skimpy, the fault can no longer be blamed on the scissors of an insensitive Jack Warner.
The picture is still a treat for eyes and ears, however, and James Mason is astonishing in his best moments, especially near the end of his character's unhappy, scrappy life. In all, it remains a solid show - but the added minutes don't transform it into anything more than that.
The Leopard was completed in 1963 by Luchino Visconti. Running just over three hours, it was cut to about 160 minutes and dubbed in English for its American release. Its current reissue restores the fugitive footage - and also the Italian dialogue - including, ironically, the dubbed Italian that comes from the lips of star Burt Lancaster.
He plays a Sicilian nobleman of the 19th century, intent on keeping his family, his values, and his sense of order intact during a time of revolutionary social change. In his usual fashion, Visconti unfolds the story at a stately pace - allowing himself, us, and the characters plenty of time to meditate on the events that transpire.
Thus the film's leisurely pace and impressive length are as much a part of its strategy as the muted colors and carefully chosen camera movements. The effect is vintage Visconti - operatic, mannered, sometimes distancing but always deeply intelligent. The restored ''Leopard'' is a memorable experience even when it fails to be an immediate and involving one.