It is sometimes difficult to track down a subject after a photo has been taken and there is less incentive for the subject to sign a release.
But sometimes investigators are commissioned to track down the subject of a programme so they can be given a right of reply.
Smitten with the woman depicted in the painting, Bougainville decides to track down the subject: Lisa del Giocondo, the wife of a Florentine nobleman.
Archived samples present a unique challenge in that there is no valid consent and it is not always possible to track down the subject to get "fresh" consent.
The story is this: Hernandez, a 26-year-old who lives in Bakersfield, California, would track down the subjects of nude pictures acquired from compromised cloud accounts, forcing them to send him more under the threat of having them all released publicly.
The information the hackers are gathering is authentic, and the intention is to provide it to the authorities to help track down the subjects.
Now, to mark its 50th anniversary this year, Shelter is trying to track down Hedges's subjects, an exercise that will highlight how people's life chances can be heavily influenced by their inability to gain access to decent housing.
Its author has tracked down his subject's schoolmates, colleagues and the unexpected figure of a former girlfriend.
It's pretty traditional four-part drama, about a photographer who scorches his own reputation by doctoring a shot, and tries to redeem himself by tracking down the subject of a photograph he took during the Tiananmen Square protests in 1989.
Wild Swans gave the couple the financial independence to spend a decade tracking down their subject "like a pair of detectives", while also opening doors to an eclectic collection of more than 200 international figures including the Dalai Lama, Imelda Marcos and Henry Kissinger.
They knew it wouldn't be the party line". Wild Swans gave the couple the financial independence to spend a decade tracking down their subject "like a pair of detectives", while also opening doors to an eclectic collection of more than 200 international figures including the Dalai Lama, Imelda Marcos and Henry Kissinger.
