WASHINGTON'S movie complexion is changing fast. Such larger theater chains as AMC, General Cinema and United Artists have begun edging into the area. Toronto-based Cineplex Odeon (which purchased the NTI chain) plans to open a multitheater site in December on upper Wisconsin Avenue -- where Johnson's Flowers used to be. And United Artists is scheduled to build an 11-theater complex in Bethesda by early 1989.

"They're all here or on the way," says Paul Roth, who is among the local owners (including Roth Enterprises, Circle Theaters and K/B Theaters, as well as the Key's David Levey and the Biograph's Alan Rubin) keeping tabs on the new chains on the block.

For moviegoers, the new spate of competition translates into better screens and sound systems in some old favorite theaters and either better new theaters or more new theaters -- such as the Key Theatre's addition of three screens to its previous one screen, two years ago.

It also means new cosmetic changes -- such as carpeting, lobby design and new seating. In addition to revamping sounds and screen where possible, Roth's has changed its interior look considerably with pastel colors instead of the all-primaries of yesteryear. The Key Theatre added three theaters to its previous one two years ago. And Circle Theaters want to make their theaters "more accessible," says Freeman Fisher, director of advertising and promotion. Moviegoers will discover suddenly "there's a quality theater near them because, with the extra competition, we're building better mousetraps."

"It's made us aware of having to update," says K/B's Ron Goldman, "and to keep our standards as good as those companies, which is a good thing."

K/B, whose spacious 850-seater K/B Cinema on Wisconsin Avenue holds the grossing record for Washington (more than $130,000 for the 1980 "The Empire Strikes Back") plans to build several new complexes over the next 20 months in the District, Maryland and Virginia, some possibly outside the Beltway. In the past six months, K/B has updated its Fine Arts, Cerberus, Janus, Congressional and Cinema 7 theaters, and plans to refurbish the Cinema next spring.

The Cinema, Goldman says, will have a "total facelift" with new seating, carpeting and wall drapes and an "eclectic color scheme." And the speakers for the already-Dolby system, as well as the projection booth, will be modernized.

K/B's best theaters, he continues, are the Cinema and Fine Arts, each with 70mm projection and Dolby stereo. Some industry authorities, Goldman says, have called the Cinema's sound system second in the East only to New York's Ziegfeld.

The Biograph in Georgetown, now holding repertorial fort since the Circle Theater disappeared, rehauled its infamous chairs last spring for plusher sliding seats. It has also added floor lighting along the aisles and recarpeted the lobby.

Circle Theaters, which owns 19 Circle and Showcase theaters, also has ambitious revitalization and expansion plans. It will have 21 theaters (comprising 66 screens). It has already revamped (or will soon) its West End, Outer Circle, Avalon, Embassy and Uptown. Plans, says Circle spokesman Freeman Fisher, include:

Turning the former Dupont Circle into a "New York-style theater" -- five screens, two of them in the 200-seat range and "some of the plusher seats Washington's seen." The films shown there will be an extension of Circle's West End's programming -- independents and foreign first-runs.

Creating a multiplex on the site of the former Circle Theater on Pennsylvania Avenue, by late 1989. Now a parking lot, the site will soon be an office building; the theaters will be in the basement. Six or seven screens will show fare similar to the West End and Dupont, but one screen will feature the kind of repertory films the old Circle used to show for years. Circle hopes to incorporate old Circle memorabilia into the new design -- including the old marquee and the clock that used to hang next to the screen.

Making a foray into the suburbs with the new Circle Shirlington, at the Villages at Shirlington Center. This new theater will have a 70mm screen, plush decor and seven screens. The programming there will be "mainstream commercial."

By early spring 1988, add four screens to the Showcase Manassas Mall 7 -- making it the Showcase Manassas 11.

Pricily overhaul the Circle Uptown, which has Washington's popular wraparound screen.

On the present parking lot on upper Wisconsin Avenue (opposite Sears) build a Tenley Theater 7 by 1989.

Roth's, which recently opened the Roth's Germantown 6, hopes to complete the Roth's Wheaton Plaza 7 by the end of next month. According to Paul Roth, the Germantown is Roth's best theater, with its pastel designs and Kintek sound system. And the Wheaton will be the chain's 13th location in the metropolitan area. (Roth's also has theaters in the Carolinas, Pennsylvania and farther reaches of Virginia and Maryland.)