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Advanced Imaging Magazine

Updated: July 8th, 2008 05:26 PM CDT

Machine Vision: No Longer Based on Borrowed Technology

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FEATURE

Machine Vision: No Longer Based on Borrowed Technology

Should machine vision continue to rely on borrowed technology? Those attending Photon02 considered that very question...

by Don Braggins

January 2003

dual-slope "gamma"
A dual-slope "gamma" (above) can be introduced into CMOS sensors capable of dealing with greater dynamic range than single-slope (below).
(Photos: Lou Hermanns, Fillfactory)
single-slope
crash test results
The results of a crash test, captured by a Fillfactory sensor with a 1000 full frame/second capability, up to 60,000 per second if frame size is reduced. (Photo: Lou Hermanns, Fillfactory)
image
Above and below: "Cloudy Day" illumination makes it possible to read characters on a crumpled aluminum foil pack. (Photos: Marcel Laflamme, RVSI-NER)
image

The biggest optoelectronics event ever to have been held in the UK, a conference known as Photon02, plus the exhibition Photonex, took place at the beginning of September in Cardiff, the capital city of Wales. The UK Industrial Vision Association worked with the organizers of Photon02 to provide a one-day workshop on the theme that machine vision no longer needs to rely on borrowed technology. (Copies of the PowerPoint presentations given at the workshop can be freely downloaded from the UKIVA website, www.ukiva.org.) This is an all-too-brief summary of the presentations given in Cardiff.

BORROWED TECHNOLOGY-AND WHAT WAS WRONG WITH IT
Machine vision for industrial applications emerged at about the beginning of the 1980s, though there were some isolated earlier instances. At that time, the choice of camera was either a thermionic tube camera (Vidicon, Plumbicon, etc.) designed for closed circuit television work or one of the relatively few solid state cameras designed to be a plug-in replacement for the tube cameras. For lenses, one either used CCTV lenses or went to the local photographic shop for an SLR camera lens.

For illumination, the photographer might also provide lamps which could be extracted from a copying stand, or fluorescent or quartz halogen lamps designed for room illumination could also be used. Vision practitioners soon discovered that ordinary fluorescent lights could cause cyclic variations as the free-running image capture frequency "beat" with illumination which rose and fell with the cycles of the power supply. Fortunately, lighting experts had already realised that some people can "see" this fluctuation of fluorescent lamps and had developed high frequency, or DC, power supplies to make them better for use in demanding situations-so machine vision "borrowed" them, too.

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