CINCINNATI, SEPT. 27 -- Four men and four women were impaneled here today to judge the first obscenity case against an art gallery in U.S. history.

Two live within city limits. The Supreme Court has ruled that obscenity cases are judged by "community standards," and the defense argued unsuccessfully that the relevant community is the city proper.

None of the jurors has ever visited the Contemporary Arts Center or seen the controversial Robert Mapplethorpe photography exhibition, from which the charges stem.

Opening arguments in the case will begin Friday, probably after the jurors go on a field trip to the arts center at the defense's request. The Mapplethorpe show is no longer on display there.

The arts center and its director, Dennis Barrie, are accused of violating state obscenity law and a statute barring possession of material depicting a minor in a state of nudity. The indictment cites five homosexual and sadomasochistic images and two portraits of children whose genitals are visible.

Candidates for the jury had to walk a fine line during four arduous days of questioning to avoid challenges from either side. The defense was sensitive to bias against homosexuals, while the prosecution generally excused those who showed much interest in art.

Judge David Albanese was reluctant to dismiss jurors even if they expressed strong doubts about their objectivity or showed firm opinions about the case. Today, for example, he declined to dismiss a woman, wearing a red, white and blue ribbon on her dress, who worked for a local church during the tenure of a pastor who founded the National Coalition Against Pornography and the Religious Coalition Against Pornography.

She said she had attended a seminar sponsored by one anti-pornography group and requested to be on the mailing list of another. She had seen photocopies of two Mapplethorpe pictures and said, "I do not believe the photos should have been shown in a museum." But she said she could be fair in the case. The defense used its last peremptory challenge to dismiss her.

The jurors selected: :

A young woman, the sixth of seven children, who is engaged. She lives in the city and works at an athletic clothing store. She said she wouldn't care to see an exhibit of photographs of homosexual activity but conceded that others might. She hasn't visited museums except for a school trip to the local Museum of Natural History. She's Catholic and accepts her church's view on obscenity. She believes sexual activities between persons of the same sex should be restricted by law.

A young secretary at a technical supply company. She and her husband are separated. She read about the Mapplethorpe show last spring but wasn't too interested in the controversy. She's a Methodist who attends church irregularly. She believes in laws against obscenity.

A middle-aged father of five who has worked as an electrical engineer for Cincinnati Gas and Electric for 27 years. The Smithsonian is the only museum he has ever visited. He's a graduate of Purdue and took an art appreciation class "to get a good grade." But he's no connoisseur. "There may be an art contest and the picture that's in first place may look ridiculous to me," he said. He said he wouldn't be offended if a museum displayed pictures of homosexual activity.

A middle-aged data processor who has three children and lives in the suburbs. Art has never been a major interest but he couldn't think of any material that should be off limits to adults. He said he wouldn't be offended by a display of works depicting homosexuality. Through his office, he contributed to the local Fine Arts Fund because "it's necessary if we want to improve our living style" and attract more corporations.

A 19-year employee of Procter & Gamble, the only black juror. She is an export coordinator, married with one child. She lives in the city. She said she glanced through the Mapplethorpe catalogue at work and said she may have thought the controversy "wasn't really necessary." She has strolled by the arts center and looked in the window; "I'm just drawn to colors, I guess."

A young, married X-ray technician who said she belongs to a church but disagrees with "a lot of their views." She has no opinion on laws restricting homosexuality. She believes in obscenity law but hasn't thought much about the issue. She had some curiosity about the Mapplethorpe show and, having sat through jury selection, she said she is curious to know more about the artist.

A warehouse manager and father of two who lives in the suburbs. He said he had no opinion on whether anti-discrimination law should protect homosexuals but said he doesn't believe the law should restrict what adults can see.

A grandfather and 36-year employee of Cincinnati Bell who said he avoids the downtown area because of traffic. He said he believes in obscenity law. He agreed with the statement that "art doesn't have to be pretty." $RAY; Invalid basket name SY/WIRE