HYPERSPECTRAL IMAGING
Taking spectral science out of the lab
Andrew Williams on the uses and current state of hyperspectral imaging, along with the technique’s potential as an industrial inspection tool
I
n recent years, the amount of commercial and industrial applications of hyperspectral imaging has continued to increase. So, what
are the main current and potential industrial and commercial applications? What are the key benefits and challenges of using the technology? And what innovations and trends can we expect over the next few years?
Farm to fork For several years, hyperspectral imaging has been used for aerial photography in agriculture and forestry, for example to detect forest damage and record forest dieback. Te European Union uses it for regular aerial inspections of farmland, making it possible to determine whether grants for growing a certain crop are justified. Farmers can use hyperspectral imaging to
determine how much fertiliser to apply to crops. Te technology can also indicate when crops are ripe for harvesting – constituents of
fruits, such as sugars and acids, emit certain colour spectra, which hyperspectral imaging can detect through the peel. Tis opens up the possibility for automated harvesting with devices like apple-picking robots, or sorting individual wheat varieties into different quality grades. Te technology also supports automated potato harvests, so that tubers can be distinguished from stones of similar appearance. Elsewhere, hyperspectral imaging is
increasingly used for quality control in the food industry, where it can be used to detect otherwise invisible layers of mould on bread or other foods, or establish the quality of fresh meat by determining fat content or levels of bacterial contamination. ‘In contrast to conventional cameras, hyperspectral imaging detects dents under the peel of an apple that are not visible to the naked eye,’ explained Dr Wolfgang Eckstein, co-founder of MVTec Soſtware. ‘Tis enables poor-quality fruits to be automatically and reliably sorted out, before they are put out for sale.’ Mark Williamson, director of corporate
market development at Stemmer Imaging, agreed that food analysis is a major market, and pointed to interesting applications like the identification of insects and animal remains in pulses and grains with ‘very positive near- 100 per cent detection rates’.
Other possible application areas include
mining, where Eckstein said the technology is used to separate ore from rocks, and recycling, where it is employed for plastic sorting and wood recycling, as well as to identify a wide range of components in rubbish, helping to optimise the separation of reusable materials from waste. Te pharmaceutical industry also benefits from hyperspectral imaging techniques, where the ingredients of medicines can be determined to make sure the right drugs are placed in the right packaging. It can also identify counterfeit pharmaceuticals.
Detecting complex patterns Eckstein noted hyperspectral imaging is of key interest for machine vision applications, with the main benefit being that it ‘reveals things that remain hidden to conventional cameras and even the human eye’. ‘Hyperspectral cameras can identify certain
objects and scenarios much more effectively by reliably detecting material properties. For example, Halcon, MVTec’s machine vision soſtware, contains a large number of functions that can be used to identify objects through the gradation of different grey-level values,’ Eckstein said. ‘Te slight differences in colour tone
indicate certain product properties and detect faults or damage. As a result, such technology
Hyperspectral cameras can distinguish between different plastics in recycling plants
24 Imaging and Machine Vision Europe • December 2017/January 2018 @imveurope
www.imveurope.com
Perception Park
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