"The Image of the Black in Western Art," the sketch of a show that goes on view today at the Smithsonian Institution's Museum of African Art, 316 A St. NE, surprises by its lack of bigotry, of stereotype. For we see here that the blacks portrayed by whites -- in ancient Egypt, Greece and Rome, and in the Middle Ages -- were more often worshiped than they were despised.

Though some of them are devils, many more are saints -- and kings and queens and warriors, charioteers and scholars, chess players and acrobats. The ruinous prejudice, the small-minded terror that so often has corroded the way whites portray blacks is, this show suggests, of recent derivation. The blacks we see here -- in these glossy photographs of ancient works of art -- instead tend to be such men as Taharqa, the Kushite conqueror of Egypt, and the scholar Memnon of the 2nd century B.C., and Balthasar, the Wise Man, who adored the newborn Christ.

This show will soon begin a three-year tour under the sponsorship of the Smithsonian Institution Traveling Exhibition Service. It was organized by the Menil Foundation, and the Institute for the Arts, Rice University, which, 20 years ago, began "a systematic investigation of the iconography of blacks in Occidental art." That survey has produced, already, three thick and learned tomes. The 74 photos in this exhibition were culled from the 817 that illustrate those volumes.

Dominique de Menil, whose idea it was launched the study in 1960 on "an impulse prompted by an intolerable situation: segregation as it still existed in spite of having been outlawed by the Supreme Court in 1954." If one looked, she was quite certain, one would come across "many works of art that contradicted segregation." Hundreds were discovered. They were made by anonymous Egyptian sculpters, French cathedral carvers, Italian mosaicists, Greek potters and Bulgarian goldsmiths, as well as by such masters as Hans Memling, Albrecht Durer, Rogier van der Weyden, and Hieronymus Bosch.

These strangely varied images confound our expectations; no single attitude toward blackness unifies this show.

"When we embarked, years ago, on this investigation," write the scholars responsible, "we had no idea of the unforseen byways and unexpected depths to which it would lead us . . . Who would have supposed that St. Maurice would turn back in the middle of the 13th century? Who would have imagined how long it took for the black king to be accepted among the Magi? . . . Surprise awaited us at every turn."

A number of these portraits -- the Durer drawings, for example -- are absolutely straight, untouched by fear, exoticism, idealization or debasement. In many others blackness takes on symbolic meaning. Sometimes it's a blessing, sometimes it's a curse. In one Spanish manuscript we see a black man burned for sleeping with a white woman (she was to have been burned too, but the Virgin Mary saved her); yet we are just as likely to see a white King Solomon happily embrace a black Queen of Sheba. Because some religious artists equated blackness with sin, and sin with death, the devils that they painted tend to be dark skinned. It is a handsome black executioner who -- in a carving from the facade of Rouen Cathedral -- draws his sword to cut off the head of John the Baptist. Yet when St. Maurice, the patron saint of the Holy Roman Germanic Empire, suddenly turns black in 1240, it is because his blackness was read then as a sign of grace -- and as a symbol of the empire's universal sway. The great Mathias Grunewald portrays him in one painting illustrated here in a golden halo, wearing fine white gloves.

We see Christ in one remarkable 13th-century mosaic rescuing two captives, one white and one black. That image was the seal of the Trintarians, a religious order devoted to the ransoming of those captured by Mediterranean pirates and then sold to the Moslems.

The blacks portrayed are sometimes slaves -- and sometimes kings. In Hans Memling's "Adoration" the black king wears golden spurs and a coat of gold and velvet; in Bosch's vision he wears pearls at wrist and ear; in Durer's he has ostrich plumes on his jeweled cap.

"We are confronted," writes de Menil, "by a gallery of blacks. A great variety of people, some plain, some beautiful, some even quivering with life. Yet all have been cast in roles they did not create. They are actors in plays written by whites. Though whites are invisible, their presence is felt everywhere. It is their customs, their taste, their prejudices, their phantasms, and their romanticism that has been captured in these images."

Were there works of art here, this would be a truly splendid exhibition. But even as a photo show it is, despite its slimness, worth examination. It will begin its tour after closing here Nov. 9.