FOUR NEW EXHIBITS at the Washington Project for the Arts offer relief from the heat, humidity and humdrum of summer in Federal City.

Ranging from traditional oil paintings through computer-generated images, the works are by four artists who live and labor in the Washington area but have nothing else in common except excellent command of their mediums.

Mildred Baldwin, 33, is a Corcoran School of Art graduate whose warm and softly lighted domestic interiors celebrate the Carolinas where she was born and raised. Baldwin's sentiment never strays into sentimentalism; her straightforward scenes take their nostalgic power from her cool and subtle colors and composition and, especially, her masterful use of light.

Light is in fact the real subject of many of Baldwin's compositions, such as "Saturday" (1988), in which family members simultaneously are sidelighted by the television set on which they're watching cartoons and backlighted by morning sun filtering through a magnolia tree.

Baldwin's work will make any Southerner want to be back home again, and should stir strange vague longings in Yankees, even.

Nancy J. Freeman, 41, studied painting before switching to computers and laser printers. Her computer-generated images reflect that traditional training; they are pixel paintings rather than trite and mindless mechanical productions.

Freeman's "generations" are shifting and subtle, with faces and other forms transmuting in complex patterns that challenge the ability of the eye to follow. When printed out, her images are rich and many-layered. It is becoming clear that "computer art" is not necessarily an oxymoron.

Nancy Palmer, 45, a professor at the Corcoran School, uses photocopiers to explore the boundaries between art and wallpaper. Four of her works, made up of endlessly almost-repeating, almost-random, abstract reproductions are stapled to the walls of WPA's main lobby. They are huge and vivid, yet have the eerie quality of seeming to almost disappear when one tries to focus on any part of any one of them. This may be the time to buy Xerox stock.

Stephen Frietch, 38, gives new meaning to the old expression about minding your own beeswax. Frietch paints with beeswax -- the ancient method known as encaustic -- which gives his rigidly rectangular abstracts a depth and translucence that belies their apparent similarity. If you've seen one Frietch painting, you'll recognize them all.