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Guns, knives, and bombs: spotting weapons in baggage x-rays

At security checkpoints in airports, screeners look at X-ray images of baggage to search for multiple types of weapons, including guns, knives and explosives.

In these X-ray images, colour is often used to represent different types of materials. By monitoring eye-movements during visual search scientists are finding ways to potentially make search easier. This exhibit will demonstrate state of the art eye-tracking technology and explain the theory behind searching for multiple targets at once.

How does it work?

By monitoring eye-movements during a visual search, scientists have found that, when looking for two colours, people spend a disproportionate amount of time looking at objects that are unlike both targets, and not enough time looking at objects that could be targets.

The fundamental limitation on a visual search that we have identified has implications for many complex screening situations. Could security screening be enhanced if screeners conducted two separate searches for threat items, e.g. one for metal-threats followed by one for IEDs? The latest research involves evaluating whether the same cost occurs in 3D images, or whether the presence of depth in images can facilitate the interpretation of overlapping objects (e.g. as found in baggage X-rays), and thus potentially improve search accuracy.

See all exhibits from 2011