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Last Updated: Monday, 13 September, 2004, 07:58 GMT 08:58 UK
Lens does away with blurry snaps
By Jo Twist
BBC News Online science and technology staff

Camera phones
Blurry images are caused by "lost information"
A specially shaped camera lens and processing method to ensure images are always in focus has been developed.

Physicist Dr Andy Harvey said it was a "simple system with a simple lens" which uses an optical encoder so that no information in images is lost.

Developed primarily for military night vision cameras, the technology could find its way into camera phones.

The quality of picture phone images is fast improving, with more models now capable of 1.3 mega pixels per image.

Dr Harvey, an optics expert from Heriot Watt University and chair of the Optics and Photonics Division of the Institute of Physics (IOP), was presenting the research at the IOP's Photon 04 optics conference.

Noses and trees

Depth of field and ensuring the foreground and background are sharp is an issue for many types of imaging systems.

Blurred images happen when information in the processing of the image is lost.

Dr Harvey's team, in partnership with QinetiQ, formerly the UK's defence research agency Dera, has developed an optical encoder lens for thermal cameras.

Traditional vs wavefront coding of images (Images: Dr Andy Harvey)
Traditional coding of images (l) and coding using wavefront (r)
Using wavefront coding, the system encodes the image so it always looks the same without losing any information.

Wavefront coding was originally proposed by Dr Edward Dowski, of the University of Colorado, for microscopy.

"Our system means that an image never goes out of focus; so if I want to take a picture of my nose with a tree in the distance, I can get them focused at the same time," explained Dr Harvey.

The research was of particular interest to the defence industry, he added, because the military would like every soldier to have easily portable thermal imaging equipment.

"Our particular research is aimed for military use. They use very expensive systems and as soon as they go outside, images go out of focus."

The current approach to fixing this was to add other lens elements to the thermal imaging camera in order to cancel out the effect, he said.

This can add extra weight and cost to thermal camera systems. Using extra lens systems can add half as much as the thermal imager cost itself.

"Ours is lighter and means you could have two lenses instead of five, and there are no focus knobs which wear out and add to the weight," said Dr Harvey.

The lens has a specially shaped and coated surface, but uses industry standard algorithms to encode and decode the image information.

The lens is covered with a microscale coating, about the thickness of a human hair, of germanium, a semi-conducting material commonly used in transistors and photodetectors.

"We can decode the information with a computer. So instead of 1,000s for lenses, it is 1 for a computer processor."

Pixel power

Dr Harvey said because most smarter mobile phones had computers and processing power on board, the system could eventually be used in camera phone technology.

"The requirement for military use is that the technology is low cost and that is what you need to for mobiles.

Nokia mega pixel camera phone
We have gone from low resolution to VGA, and at the moment we are approaching 1.3 mega pixels
Mark Squires, Nokia
"You want to pick up and point and always be in focus without turning knobs. What you need for the system is a computer, which all mobiles have now."

Mark Squires, a spokesperson for Nokia, said it could be a useful development for mobile cameras of the future.

"In small devices the most important consideration is size and power consumption," he said.

"Mobile phone cameras are following similar development paths as digital cameras.

"Once they have caught up with conventional technology, then the lens itself becomes important and if there is a way of improving the lens, we would look at that.

"It may have more implications for military applications initially, but it is normal to see developments for military use finding their way down the line to commercial production."

Currently, mobile manufacturers were concentrating on improving the pixel quality - the number of dots that make up an image - and size of images, he said.

"We have gone from low resolution to VGA, and at the moment we are approaching 1.3 mega pixels; the more dots, the sharper the picture. So we are upping the quality."

Nokia is just one of the mobile makers who have recently released mega pixel camera phones in Europe.

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