SEED ANALYSIS


and field crops – wheat, barley, rice, oil seed rape – but also flower seeds and tree seeds.’ Videometer began 20 years ago providing


spectral imaging for very accurate colour determination in production – sorting based on very subtle nuances of colour. ‘Spectral imaging is a mature technology,’


Carstensen said, ‘but it’s something that’s specialised in terms of who is providing it, because the data is massive and you have a lot of opportunity to get noise instead of signal. ‘Spectral imaging cameras and


components are only part of the solution,’ he continued. ‘A true solution for the industry would have to integrate a lot of components: illumination sources and illumination geometry, cameras, controlling electronics, machine learning – putting all this together is quite a multidisciplinary undertaking.’ Videometer only uses LEDs and has done


so for 20 years. Its systems combine a number of LEDs emitting at specific wavelengths throughout the UV, visible and near infrared range. Te LEDs are strobed in an integrating sphere extremely quickly so that the system captures each image under a different wavelength of light, acquiring images as fast


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‘We [can’t] tell the entire germination story based on the dry seed, but for many seeds we can see how viable they are’


as the camera allows. ‘Typically, we would take 20 wavelengths within half a second, calculate the data cube and analyse it to provide the result,’ Carstensen explained. He said that a lot has been made possible


by the increase in computer speed – deep learning is one example. He also said that the power-over-price in LEDs has improved, especially in the UV, where it’s now becoming feasible to do quite sophisticated measurements that weren’t possible in the past because powerful deep UV LEDs used to be prohibitively expensive. ‘We definitely believe that UV is important


for spectral imaging,’ Carstensen said. ‘Te challenge is that normal optics will not go to a shorter wavelength than 400nm, sometimes 350nm. You need specialised optics that are more expensive, and still hard to get – there’s


not a lot of choice when you go down to UV optics. You can get them, but if you have specific requirements within the UV range you run out of suppliers very quickly.’


Separating the wheat from the chaff Te seed companies that Videometer works with and that have been discussed so far are producing seed that will be sown to grow into a plant. But what about grain harvested for food? Te Swiss R&D organisation, CSEM, has worked with machine builder, Bühler, to improve quality control on one of its milling machines. Sébastien Blanc, senior R&D engineer at


CSEM, spoke about the project at the Vision show in Stuttgart in October. Te problem Bühler presented CSEM with was to reduce the error rate when measuring the mass flow of grains passing through its milling machines. Bühler’s machines typically use a deflecting plate in the shoot to measure the force of grain passing down it and from that calculate the mass flow. Without an accurate mass flow


measurement, grains of different quality get mixed together – Bühler was registering error rates of up to 8 per cent in mass flow,


g OCTOBER/NOVEMBER 2021 IMAGING AND MACHINE VISION EUROPE 21


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