The famous whisper is still there. But the image, as Jacqueline Onassis first took the stand today in what she called "the ordeal of court" against longtime nemesis Ron Galella, was somewhat modified.

She clasped her hands, her voice wavered, she gulped as she testified in U.S. District Court on her complaint alleging that the celebrity photographer had violated a 1975 court order barring him from approaching within 25 feet of her and 30 feet of her children. But when she had been on the stand for nearly two hours and Marvin Mitchelson, the California lawyer representing Galella, had given her an opportunity to recite her long list of grievances, the nerves had begun to turn to composure and anger.

Hadn't Onassis been photographed for several years by Galella and not complained to her attorney, the defense asked, suggesting that these charges of harassment were not as awful as they seemed.

No, said Onassis, she had complained to her attorney time after time, as many times as Galella had dogged her.

"He ruined my daughter's graduation, he ruined my son's graduation . . . I thought, okay, there will be other photographers there, they just graduate once, I can live with that," she said. "He bribed his way into Hyannis, on to a private dock . . . He made it impossible . . . I used to go to Hyannis at the beginning of every summer, the happiest time of the year. That began to be gradually intolerable to me with this surveillance . . . "

Onassis wore a long-sleeve brown blouse and tweed skirt. Her hair was glowing. "Jack-leen Kennedy Onassis," she had said when asked her name, and when asked if she planned to tell the truth, a whispered, rapid "I do, I do."

The Onassis-Galella battle has continued on and off for at least 10 years, longer than many modern relationships but no less rancorous. In the early days, Galella, according to Onassis, surprised her children at play, disguised himself in sailor suits to pursue her and once even hid behind a restaurant coat rack. (The restaurant manager, Galella insisted, had invited him to hide behind the coat rack).

Those battles resulted in a suit that she did not start. Galella filed a $1.3-million suit claiming the Secret Service, in such actions as smashing his cameras and shoving him into snowbanks, was preventing him from pursuing his livelihood. Jackie countersued. The outcome in 1975 was a court order from federal Judge Irving Ben Cooper forbidding Galella from photographing Onassis and her children from close range.

And now Onassis was charging at the non-jury trial before Cooper that Galella had violated the terms of the court order, blocking her path at a theater, "tailgating" her down Manhattan streets, even coming upon her in a small boat at Martha's Vineyard.

Those wondering if time had mellowed their relationship, if there had not been some moments of bemused tolerance between subject and photographer, would be disappointed. The relationship, described by Onassis in four hours on the witness stand as Galella from time to time leaned back and rocked in his chair, smiled and laughed, was hostile and threatening.

"I said to him, 'Don't get that close to me, I'll take you into court,' " Onassis testified. "He said, 'Oh, you'll take me to court, will you, Jacqueline?' "

Though she was a public figure and used to the press and photographers, Onassis testified that in his aggressive "surveillance" of her Galella was frightening and disturbing to her and her family.

"Caroline told me Galella had nearly run her down on the road, she was very upset, agitated . . . When she told me about the sandy road it was frightening to me, I could see how spinning bicycle wheels could go under the wheels of a car . . . I said to her, 'We'll have to do something about Galella, we'll have to go into court.' I tried to say comforting words; it's hard to say comforting words because I couldn't promise relief."

Caroline Kennedy, who was in court two months ago testifying against a man who had camped out at her apartment building, testified Tuesday that Galella this year had passed her in his car on Martha's Vineyard and frightened her and a friend who were bicycling. She said Galella got out and stood in the middle of the road and shouted, "Hi, I'm a friend. What's the matter? Don't you like me?' "

Onassis, under direct examination today by attorney Edward Reilly, said Galella had harassed her on three separate occasions: at a movie on Eighth Avenue, when he pursued her into the street and blocked her path as she tried to get a cab; during Labor Day weekend on Martha's Vineyard when, using a motorboat, he suddenly came upon her, causing her boat to stall, and at a dance concert when he blocked her entrance arriving at and leaving the theater, and then pursued her, laughing, up and down Manhattan streets. She also said that in photographing her Galella frequently made "scary, grunting noises." She said Galella stopped a car chase only when she and her party in their car went to the police. That evening, she said, she was particularly disturbed.

"I was extrememly agitated, upset, desperate in a way . . . I thought Galella was going to start pursuing me all over again . . . By the time I went to bed I was . . . I was just upset."

Mitchelson, dressed in a suit that was sharply nipped in at the waist and wearing a bright silver watch and silver-rimmed glasses, pursued a line of argument that has been used in Galella's defense before: Onassis is a public figure appearing in public places, and she's newsworthy.

"Galella has not attacked her in a paparazzi manner or invaded her private life," said Mitchelson. "He's photographed her only in public places . . . Newsweek, in a photograph that is not Galella's, reports her in the same place . . . Galella has the same rights as any other inquiring journalist, a fundamental constitutional right."

On cross examination by Reilly, Galella acknowledged that he had not "fully complied" with the court order and that at times he had come within 25 feet of Onassis when photographing her. He admitted that outside the Eighth Avenue movie theater he actually came within five or six feet of her. Under direct examination, he said he was within five or six feet of Onassis because he was maneuvering to get a good picture of her.

He told the court, "I may have broken the distance (order) . . . but it was not intentional."

Questioned about how much he was paid for various photos of Onassis, Galella said he was paid $500 by Newsweek for an exclusive photo he had sold them. He said the regular price would have been around $175.

A decision on the matter is expected from the judge within a month.