"When you walk around in a big city, you don't see trees, you see windows," says artist Michael Clark. "They're timeless - like architecture - and I wanted to capture them before they're all lost."

As a result, for the past dozen years, Clark, 33, has made hundreds of paintings of windows in Washington (where he grew up), in New York (where he studied at the Pratt Institute, and now lives) and in Los Angeles and Paris, where he travels whenever he can. There are hotel windows, office windows, warehouse windows, windows in Chinatown, and more.

No less than 150 of the resulting "Picture Windows" from 1967 to the present have just gone on view at the Dimock Gallery of George Washington University, downstairs at Lisner Auditorium, 21st and H St. NW, in the artist's largest show to date. Recent drawings, also of windows, are being shown concurrently at the Lunn Gallery, 3234 P St. NW.

The real fascinaton of this show, beyond the dozen or two truly beautiful paintings, is the revelation of the expressive range Clark has managed to wrest from the self-inflicted discipline of repeated subject matter - without being merely repetitious.

It is a system artists as different as Giogio Morandi (with his bottles) and Gene Davis (with his stripes) have successfully employed. But it takes the measure of an artist's mind and creativity, and while Clark has what it takes to proceed in this manner, the results are often merely links in the chain of his thinking process. If not always splendid to look at, however, they are revealing, as is the entire show.

There are, in fact, no people in Clark's windows, though their presence is sometimes implied in the flickering blue "TV light" that emanates from within some of the rooms, and in the changing patterns of the window shades, up and down.

But where a human figure does appear - as in the one painting with a nude torso seen through a window - it is incongruous. And where a corner of a curtain seems to blow in the breeze, it is unbelievable - an intrusion in Clark's airless world.

This world is epitomized in one of his most striking recent works, which he calls "Classic Classic," or "Classic Grisaille," where all temporal elements - even color - have been removed. "I think this is as far as I can go with "Classic Windows," says Clark.

It is a wise artist who knows a culmination when he sees one. The other most important series, "Project Windows," climaxed way back in 1973 with the intimate and beautiful works shown here on the far wall. What has come since - uninteresting multiple stories of buildings (or multiple paintings of the same story) - are no match for them.

Over the dozen years represented in this show, Clark has dealt primarily, though not exclusively, with windows. There were also some fine seascapes and captivating pointillist-pop variations on Gilbert Stuart's head of George Washington, seen often at Lunn and at the Corcoran."If I could paint like Claude Lorraine, I'd paint more landscapes. For now, I'm chiefly concerned with windows, and feel they are my most original statement and express more of me than anything else I've done. But after all, I'm very young."

Despite its ups and downs, the Dimock show is a worthy and revealing one, hung salon-style, with paintings large and small covering the walls from ceiling to floor. The installation attempts to recreate the profusion of various window images that meet the eye in the course of a gambol down a city street. It is a nice conceit which helps this show, though that old curatorial impulse to give it a good weeding is almost irrepressible. Both shows continue through June 29.

Louis Andre has just announced, to the dismay of many of his artists, that he will close his WOLFE ST. GALLERY, 1204-31ST ST. NW at the end of June. The gallery first opened in Alexandria , dedicating itself to lesser known Washington artists, moving to Georgetown four years ago. "I will continue to operate as a private dealer," says Andre, "but with fewer artists whom I will be able to give better service and greater exposure outside Washington."

"Maintaining a gallery is a tremendous cash drain," he explained, "and though shows are great ego gratification, they're a dead end in the long run - brief exposure and then nothing. This way Ill be dealing with a much smaller group, no longer unknown, and will be able to go beyond the limitations Washington imposes."

Andre also revealed some interesting facts about the economics of sustaining a gallery, which he says has been costing him some $3700 a month to maintain, including rent, utilities, and part time help. "If we sell out an entire show by a low-priced new artist each month, taking a 40 percent commission, we still lose money."

Meanwhile, the gallery is showing a strong group of miniature prints, drawings and photographs by gallery artists, through today, with several collages by Lea Feinstein and drawings by Susan Davis Outstanding among them. Opening next Tuesday will be the final show, featuring photographs by Tom Shuler and prints by Charles Hewitt, through June 23 when the gallery closes for good. It will be missed.

As part of the "Japan Today" celebration, the International Monetary Fund Gallery at 700-19th St. NW, has been showing post-war Japanese prints and ceramics, a show which continues through June 1 and is well worth a visit for anyone interested in the subject.

Borrowed from several local collections (plus a few of the proliferating local dealers in the field), the IMF show seems to make the point that the woodcut revival of the 50's and 60's produced considerably better work than the post-pop, photo-silkscreen era of the 70's.

Highlights include several works by old Masters like Munakata and Washington's own Un'Ichi Hiratsuka, along with examples by Watanabe, Sekino, Saito, Sasajima, Mori and others. For an update on the more recent work, the National Academy of Sciences, 2100 C St. NW, continues to show "Contemporary Japanese Prints" organized by the Japan Foundation, through June 6th.

Not far away, the Federal Reserve Board, C Street between 20th and 21st St. NW, is currently showing "Chinese Painting from Collection of Marshall B. Coyne," a collection as bereft of first rate examples as one is likely to see in a public place.

As an exhibition label explains the enterprise, "taking advantage of the new diplomacy, Washington entrepreneur Coyne began to purchase oriental objets d'art 3 or 4 years ago." The show is an object lesson in how not to collect, and with few exceptions - among them a 16th century Ming Dynasty "Scholar with Ink Stone" - most of the works are second rate examples from the late 19th century.

If such shows are meant as an educational experience for the staff, they'd do better to take a walk across the Mall to the Freer. The best artists in this show were the staff members who designed the catalogue. Through June.

The Fendrick Gallery, 3059 M St. NW, has a chuckle-ridden show of fantasy beasts in various media from ceramic to seashells, called "The Peaceable Kindgom." Included is everything from a spectacular $45,000 brass bathtub in the shape of a life-size hippopotamus by Ffrancois Lalanne to Andrea Uravitch's cozy crochet-over-foam sleeping chair called "Joy of Pigs," one of several porkers on view. Most satisfying as art is the tenderly depicted and beautifully drawn new figure of "Goat with Goat Heads" by Joan Danziger, and Thomas Palmore's puzzling paintings of exotic birds set against a paint-by-numbers background. Through June 23.

A new show at the A. D. Smull Gallery, 1606-20th St. NW, introduces more fantasy - this time in plant forms, by an imaginative new ceramic sculptor, Barbara Mones, who has been studying and teaching at the Rhode Island School of Design. This is her first show, and consists of some startlingly large, vaguely surreal plant forms which combine seductive and threatening aspects. More approachable are several large ceramic leaves, cast from the real thing, with airbrushed underglazes which give an irridescent effect. Also on view are some endearing stitched pictures by Betsy Grob Giberson. Through June 16. CAPTION: Picture, Michael Clark with his paintings; by Harry Naltchayan-The Washington Post