U.S. soldiers frisk Iraqi motorists at a mobile checkpoint in Kadhamiya north of the capital Baghdad. Could new technology help soldiers find hidden weapons more easily? (Wally Santana/AP Photo)
Revealing Pair of Eyes

New Software Blends Images to Spot Hidden Weapons

By Paul Eng
(original report)

July 8 -- When it comes to patrolling the mean streets of post-Saddam Iraq, American soldiers could benefit from an extra set of eyes.

Since major combat ended in April, more than 40 American soldiers have been killed by Iraqi insurgents armed with hidden weapons and explosives. In many cases, such as Sunday's attack when a soldier was killed while waiting to buy a drink, the assailants often strike from among crowds of people.

But keeping soldiers and others safe from assassins hidden in a crowd may eventually become a bit easier.

Rick Blum, a professor of electrical and computer engineering at Lehigh University in Bethlehem, Pa., has been working with a team of scientists that could give soldiers and police a set of X-ray eyes.

The setup uses two cameras. One camera takes normal digital images while a separate camera uses a new chip called a millimeter-wave (MMW) sensor.

The new sensor, based on MMW radar developed by the military, emits very high frequency radio waves that can penetrate clothing and walls to reveal metal objects such as guns and knives. The resulting image looks much like an X-ray photograph.

While other researchers and companies are working to develop similar -- and controversial -- concealed weapons detectors, Blum's system goes a bit further that just revealing what's under a person's clothes.

The Best of Both Views

At the heart of the experimental system is a unique set of computer algorithms or programming code, that analyzes the images from both the MMW sensor and digital camera. The software is optimized to compare matching regions of each digital image and use only the best features and details of each.

The idea, says Blum, is that both visual and MMW images have their own unique strengths and weaknesses.

"You need to look at each image and say, 'What am I trying to get out of it?' " says Blum. "The visual image is better than the MMW image at helping to identify exactly who they're looking at. But the MMW image is good at revealing what's hidden but at the expense of [other] visual details."

Since the software is designed to show only details that is found in one image but lacking in the other, the results are stunning. An operator sees not only a normal visual of what the video camera sees but also any objects that are hidden from plain view. That makes it much easier to identify a suspicious person in a crowd and direct soldiers and police to pay attention to that particular person.

Black Eyes

Before the system can become fully operational, Blum admits that key issues still need to be worked out. Key among them: the MMW sensors.

With only two or three such sophisticated sensors built so far, "the MMW is far too expensive," says Blum. "Right now, it's just not practical."

As such, Blum is modifying his software to work with other types of sensors including infrared, and so-called backscatter radar that is currently being considered for use in airport screening systems.

And like those other screening systems, there remains the question if such weapons detectors could be used in the United States without violating laws against unreasonable search and seizure.

"The use of anything that is invasive for general purposes -- capturing everyone that comes in the scope of the technology -- really does raise the most serious questions," says David Sobel, general counsel for the Electronic Privacy Information Center in Washington,. D.C.

On the Move

Blum believes that the system could still find eventual use among the U.S. military -- especially among forces deployed in peace-keeping roles in other nations. By equipping troops with such technology, soldiers would be able to spot potential enemies without resorting to physical body searches and potentially alienating peaceful bystanders.

"It would be great to be able to give this technology to police and to military troops in Iraq," said Blum in a press release from Lehigh University.

In the meantime, Blum is seeking additional funding from the Department of Defense for further research and development. He hopes that a portable prototype can be developed for field trials soon.