Grampian Police Constable George Hall, 44, who denies trying to extort hundreds of pounds from Lynn Morrison, went on trial on Tuesday. The offence is alleged to have happened at her home in Cruden Bay, Aberdeenshire, last year. The officer has gone on trial at Peterhead Sheriff Court.
It is claimed Constable Hall told Ms Morrison that unless she paid him he would show the "naked and indecent" photographs of her in public.
This allegedly placed Ms Morrison, 33, in a state of fear and alarm.
PC Hall, also of Cruden Bay, faces an alternative charge of breach of the peace by causing Ms Morrison to believe he would display naked and indecent images of her in a public forum.
Giving evidence on the first day of the trial, Ms Morrison - who was assisted in court by an interpreter - said she first got to know the police officer when she began babysitting for his children.
She said they began a relationship around August 2003 and PC Hall had taken photos of an intimate nature of her on a digital camera. Ms Morrison said she also took photos of herself using the camera's automatic timer.
Procurator fiscal Sandy Hutchison asked: "These photos, did you consider them a private matter or photos that could be distributed elsewhere?"
"No, no, very private," she said.
Ms Morrison said the photographs had been loaded onto both PC Hall's computer and her computer.
The court heard that during their relationship, Ms Morrison borrowed £500 from PC Hall as she owed her sister money.
"At its best, how would you describe your relationship with Mr Hall?" asked Mr Hutchison.
"It was love, the relationship was good," she said.
Ms Morrison added that at that time she was happy for the photos to be taken.
"It was boyfriend and girlfriend, it was about the relationship and we trusted each other," she said.
The court heard that Ms Morrison had paid PC Hall back £200 but still owed him £300 when their relationship ended in August 2004.
It was claimed that Ms Morrison started getting text messages from PC Hall in January 2005 "bothering" her over the amount she owed.
She told the court that on 3 March, 2005, she received a text message from PC Hall which prompted her to contact the police.
"It said if I did not pay the money back he would put images of me naked on the internet," she said
The fiscal asked: "The threat of him putting naked images of you on the internet, did you consider that related to the images of you still on his computer?"
She said: "Yes and it was shocking - I did not still know he had these photos of me and I was very shocked by that because these were such private things."The trial continues.