Taking good photos underwater requires a good white light source such as a flash or spotlight. But some wavelengths of light penetrate water more easily than others, and the result is a heavy blue cast.
The tint gets progressively deeper as subjects get further from the camera, meaning that corrective filters only work for a narrow range of distances from the lens.
Filters cannot always be changed quickly, or even at all, say Daniela Rus and colleagues at the Massachusetts Institute of Technology. For example, they say filters are little use for remotely operated cameras like that on a robotic submarine.
See clearly now
Their new patent application suggests the solution is to use a camera with a battery of different flashes. Each produces a different wavelength of light, which penetrates water to different extents. A sensor records that effect, making it possible to work out the distance to a subject in the image.
It is then possible to generate the perfect wavelength of flash to show the subject in its true colours. The result should be naturally coloured underwater photographs.
Read the full patent application for natural-colour underwater photographs.
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