How does photo ageing work?
Police have issued a picture of how Madeleine McCann might look now after she disappeared from a Portuguese holiday resort. But how do you go about ageing someone?
Madeleine McCann’s face is probably one of the most recognisable in the world, but it is the face of a four-year-old Madeleine and that is the problem.
Two-and-a-half years after she vanished from a Portuguese holiday flat, police issued age-progressed images of how she may look today.
They are aimed at “pricking the conscience” of people who know what happened to her. But how are the pictures created?
Police use specialist age-progression artists to generate such images. They use different techniques, including drawing, but usually produce computer-generated images.
There is no specific age-progression software, but the artist uses existing computer packages to manipulate features.
As a child grows their eyes will largely stay the same but everything below the eyes grows outwards and downwards, says age-progression artist Auriole Prince.
“Trying to show how this growth changes a face is like piecing together a puzzle,” she says. “There’s an upside down triangle between the eyes, nose and the mouth. The relationship between these features is the most important in keeping the likeness.”
Ideally an artist will have an original portrait-style photograph of the person who is going to be age-progressed, along with other photos showing them at different angles and with varying expressions.
They also use photographs of other family members. As a rough guide, 70 to 75% of an age-progressed face can be extrapolated from pictures of the subject’s parents taken at the same age as the child, says Ms Prince. Pictures of siblings will also be helpful.
Along with artistic skills, age-progression artists also need to have a good knowledge of the anatomy of the face. This is because bone growth and dental changes can have a real impact on what a person looks like, especially at certain ages.
“From age four to six, like Madeleine, a person will go through a lot of changes,” says Ms Prince, who works with police and also worked for the National Missing Persons Helpline for eight years. She trained in the US with the FBI and the National Center for Missing and Exploited Children.
“But some of the biggest alterations take place from age seven to eight. This is because a person’s underlying bone structure really grows, milk teeth fall out and the new teeth emerge.”
Contrary to popular belief, a child’s eyes do not remain the same size from birth. But their growth is minimal compared with the lower face. However, an age progression artist will sometimes shrink the iris- revealing more whites of the eyes – to imply aging, says Ms Prince.
In cases of vanished children, the child must usually have been missing for at least two years to warrant an age progression image, says Ms Prince. The child must also tend to be at least two at the time they went missing.
In terms of success in reproducing a likeness, Auriole Prince stresses age progression is more about renewing publicity and moving on the public’s perception of a person, than creating a facsimile of what a person may look like. They are often used in long-running missing persons cases like Ben Needham, who disappeared on the Greek island of Kos in 1991.
“In this case the public will still be looking for the four-year-old Madeleine and the police want them to look for six-year-old girl,” says Ms Prince.