Coloured X-ray of a barn owl. A physicist has used X-ray to create an extraordinary collection of artwork. Arie van't Riets pictures reveal birds, fish, monkeys and flowers in an incredible new light. The 66-year-old, from Bathmen in the Netherlands, began X-raying flowers as a means to teach radiographers and physicians how the machine worked. But after adding a bit of colour to the pictures, the retired medical physicist realised the potential for an exciting new collection of art. (Photo by Arie van't Riet/Barcroft Media)

Audrey Hepburn cooking at home, 1954. Colorized by Dana Keller.

Young Japanese women pose with a green bear costumed person during the 'Earth Parade 2015' in Tokyo, Japan, Saturday, November 28, 2015. Ahead of the U.N. climate change summit in Paris starting this week, about 1,000 citizens and environmental activists took to the streets of Tokyo on Saturday, calling for strong actions to combat global warming. (Photo by Franck Robichon/EPA)

A glamour model Lacey Banghard attends a photocall for PETA to encourage pet owners to have their cats and dogs sterilised at Picadilly Circus on January 22, 2013 in London, England. (Photo by Ben Pruchnie)

Members of the organization Witness Against Torture wear orange prison jump suits with handcuffs and a hood over their heads during a demonstration urging the government to close down the detention facility at Guantanamo Bay, in Lafayette Park outside the White House January 11, 2012 in Washington, DC. Protesters carry on a 92-hour vigil in a protest of the 10th anniversary of the arrival of the first group of detainees to arrive at the US military facility (Photo by Astrid Riecken/Getty Images)

Colored Pencil and Origami Landscapes: Ivanova's version of the popular Snake game features a chain-link origami snake chasing a butterfly. (Photo by Victoria Ivanova)

A girl reacts as coloured water is thrown on her face while celebrating Holi, the Festival of Colours, in Mumbai, India, March 13, 2017. (Photo by Shailesh Andrade/Reuters)