Know-alls: Economist

Electronic snooping by the state may safeguard liberty—and also threaten it

Kobal Collection

IF A Muslim chemistry graduate takes an ill-paid job at a farm-supplies store what does it signify? Is he just earning extra cash, or getting close to a supply of potassium nitrate (used in fertiliser, and explosives)? What if apparent strangers with Arabic names have wired him money? What if he has taken air flights with one of those men, with separate reservations and different seats, paid in cash? What if his credit-card records show purchases of gadgets such as timing devices?

If the authorities can and do collect such bits of data, piecing them together offers the tantalising prospect of foiling terrorist conspiracies. It also raises the spectre of criminalising or constraining innocent people’s eccentric but legal behaviour.

In November 2002 news reports revealed the existence of a big, secret Pentagon programme called Total Information Awareness. This aimed to identify suspicious patterns of behaviour by “data mining” (also known as “pattern recognition”): computer-driven searches of large quantities of electronic information. After a public outcry it was dubbed, perhaps more palatably, Terrorism Information Awareness. But protests continued, and in September 2003 Congress blocked its funding.

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The computer says no: Economist

Image processing could help to identify artists by their brushstrokes

THE ability of computers to analyse complex digital images is growing rapidly. Robots are being fitted with powerful vision systems that allow them to recognise and hold things. Satellite images of the Earth can be scanned for tiny features, or pictures from deep space searched for strange objects. Medical images can be analysed to find out what might be going on inside a human body. Now digital imaging is learning how to spot art forgeries too.

Scientific methods have long been used to help authenticate works of art: for instance, paint can be dated from its chemical composition or canvasses X-rayed to reveal what lies below the surface. In recent years, however, the art itself has come under more scientific scrutiny, especially through the analysis of brushstrokes. The idea is to establish the equivalent of an artist’s “handwriting” to help experts attribute paintings.

One of the most comprehensive studies using such methods was published recently in Signal Processing Magazine from the Institute of Electrical and Electronics Engineers. It involved analysing the paintings of Vincent van Gogh and was carried out by James Wang of Penn State University and his colleagues from other universities. It was done with the help of the Van Gogh and Kröller-Müller museums in the Netherlands.

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