New app can reveal painting's past with just a swipe

A new app for smartphones and tablets lets users see the path a painting took from sketches to completion, from any angle.
Repentir, the free app developed by researchers in the UK's Newcastle University and Northumbria University, works with only one painting so far.
It can reveal the history of "Transamerica," a new painting by artist Nathan Walsh.
However, the developers believe that the technology could soon be applied to many new paintings, and maybe even old ones, LiveScience reported.
"What you could do is take the actual imagery art historians have been making of old paintings and actually use the app as a way to reveal them," said Jonathan Hook, a professor at Newcastle University.

"Transamerica" is a street scene as seen reflected in a San Francisco Chinatown gift shop. As he painted, Walsh took a photograph every day of the unfinished canvas, starting from pencil sketches and ending in oil paint.

Hook and his colleagues then compiled these photographs into layers. Repentir app users can scroll through the layers using a scroll bar, or they can rub top layers away on-screen with a fingertip, revealing the earlier work underneath.
Viewers can snap a picture of the artwork from any angle as they view it in person, and the programme will recognise the picture and adjust the layers accordingly.

This means that you can even get up close and photograph just a tiny portion of the picture and the app will still recognise it, Hook said.
Repentir currently needs "Transamerica" to work, but any artist with digital photography equipment could join the project, Hook said.