The woman was walking alone along Oswald Road when the incident occurred.
Detective Inspector Alan Bentham said of the incident: “We have previously issued an image of a man we would like to speak to but who we have yet to trace.
He continued: “The latest images are enhanced and our hope is that someone will recognise the man and get in touch with us.
“Incidents of this nature, whilst rare are extremely distressing for the victim and the community as a whole.
“We are working with the victim and it is important that we also reassure the public that a thorough investigation is taking place.
“Our request to the community is that anyone who has information in connection with the identity of the man or knows anything relevant to the investigation comes forward to speak to us as soon as possible.
“We would also encourage people to consider their personal safety and be aware of their surroundings.
“Try not to walk alone, especially at night, but if you have to, ensure you keep to well-lit areas, busy streets, main roads and footpaths.
“Avoid badly lit areas, parks, alleyways and underpasses.”
Calls can be made to 101 quoting crime reference number 2124250.
Alternatively calls can be made anonymously to Crimestoppers on 0800 555 111.