Friday, December 2, 2011

Smart image editor adds fake objects to photos

Ever wished you could add something to a photo, without the tweak being detectable? Now a new programme developed by David Forsyth from the University of Illinois in Urbana-Champaign and his team can make the alteration while simulating lighting conditions so that the change looks realistic.
To achieve the trick, the software first recreates the 3D world where the photo was taken. A user is asked to select light sources in the picture so that an algorithm can recreate the 3D geometry and lighting of the scene and insert the artificial object into its new environment. Then the programme adds shadows and highlights to the object before converting it back to 2D. The brightness of the object is analysed and matched to conditions in the photo before it's added in.
Existing photo editing programmes simply insert a 2D object without considering the lighting and perspective of the artificial object and photo. "Humans can quickly detect photo fraud because we can accurately spot lighting inconsistencies in a photograph," says Kevin Karsch, a member of the team.
The researchers hope the programme will be useful for recreating historical scenes by adding artifacts to old photos. It could also be useful for interior design, allowing decorators to take a photo of a room and virtually experiment with different furniture.
The work will be presented at Siggraph Asia, a conference on computer graphics and interactive techniques, from December 12-15 in Hong Kong.
If you enjoyed this video, check out a system that lets you edit 3D images or see a display that shifts the shadows on a still image to reflect different times of day.

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