The Corcoran Gallery of Art yesterday announced it is operating in the black - and losing its director.

Roy Slade, 43, the artist and art educator who has led the Corcoran to renewed financial health, will leave Aug. 1 to become president of the Canbrook Academy of Art, Bloomfield Hills, Mich.

News of Slade's resignation yesterday came as a surprise to the local art community. "I can't believe it," said one museum official. "You mean he's leaving a good job one block from the White House to take another 16 miles from Detroit?"

"Cranbrook made me an offer I couldn't refuse," Slade said.

The Corcoran's deficits were increasing yearly when Slade was promoted, from head of the Corcoran School of Art to director of the museum in November, 1972.

In fiscal year 1972/73, when Slade took control, the gallery showed a deficit of $385,867. That figure was reduced to $202,521 in 1973/74 to $75,000 in 1974/75, and - according to the annual report released yesterday - stood at only $3,096 at the end of fiscal year 1975/76.

The gallery is now in the black, and as of Jan. 28, showed an operating surplus of $46,000.

While deficits have declined, contributions have increased more than 10-fold. They totaled $41,810 in 1972/73 compared to $48,557 in 1975/76.

"We are deeply sorry to see Roy go," said David Lloyd Kreeger, presient of the Corcoran trustees. He's done a superb job, the Corcoran has visibly improved under his leadership."

A search committee, headed by Washington attorney and Corcoran trustee Freeborn Garrettson Jewett Jr., will meet next week to plan a search for Slade's successor. "We are going to get the best director possible," said Kreeger. "We hope he, or she, will be on board by Sept. 1."

Slade says he is leaving because "Cranbrook offered money, security, an academic schedule, and - this is the main thing - a chance to return to the studio to paint."

Slade, a Welshman who joined the Corcoran School of Art in 1967, was a teacher and an exhibiting painter (he used to show here at ther Jefferson Place Gallery) before he became the Corcoran's administrator. Between 1968 and 1972, four men - James Harithas, Walter Hopps (now with the National Collection of Fine Arts), Gene Baro and Roy Slade - held that taxing job.

Cranbrook, which began informally in 1927, is a community of artists and craftsmen which occupies a 300-acre landscaped campus in Bloomfield Hills. It has 150 graduate students, a faculty of 12, and a large endowment of some $15 million. Much of its money came from the Booth family of Michigan, which last week gave a late painting by Gauguin to the National Gallery of Art. The Cranbrook campus houses not just the Art Academy, but a science institute and three secondary schools. The five Cranbrook institutions received more than $25 million for shares of Booth Newspapers, Inc., when that family concern was sold to S.I. Newhouse for $346 million in 1976.

In the '50s, the Art Academy was highly regarded as a kind of American Bauhaus. Many of its buildings were designed by Eliei Saarinen (architect Eero's father) and its graduates include designer Charles Eames, painter Bob Beauchamp, sculptors Harry Bertois and Duane Hanson, and architect Harry Weese, who designed this city's Metro.

As part of his pay, Slade will have the use of a grand five-bedroom house with formal courtyards and a 40-foot studio. The House was designed by Saarinen.

Cranbrook's reputation is not what it one was. "I hope to bring it back to its golden days," said Slade. "Living there will be like living at Dumbarton Oaks. I won't really miss Washington society. And I'll have time to paint. I feel like a preacher who hasn't had time to pray."

"You better be good at it, Roy," said Kreeger.