New innovative image sensor technology applications have the potential for improving processes in various sectors, such as industry, healthcare and agriculture, for example. Applications that come to mind include smart production process monitoring applications, the diagnosis of skin disorders or tracking down plant diseases. Applications of this nature and the required technology were key considerations in the development of EXIST (Extended Image Sensing Technologies). This Horizon 2020 project was headed up by the renowned Belgian research company Imec. Participants included companies and research institutions from Belgium, France, Greece and the Netherlands, including Demcon Focal.
Of particular interest are the hyperspectral image sensors manufactured with the aid of semi-conductor technology. Such sensors enable a camera to make a recording consisting of sub-recordings across a broad spectrum of many different wavelengths (colors). In principle, a hyperspectral recording provides more information than a color photo taken with an ‘ordinary’ camera. Demcon Focal researched the practical application of the advanced hyperspectral image sensor developed by Imec for diagnosing bruises.
The idea was to use the hyperspectral camera for making a distinction between an accident and child maltreatment as the cause of bruising. A bruise turns blue due to the hemoglobin in the bruise. Over a period of days, the hemoglobin gradually breaks down. This in turn produces a waste material, known as bilirubin, which causes the bruise to turn yellow. The proportion of the measured quantity of these two substances can tell us something about the age of a bruise. In case of an accident all bruises should be approximately the same age. In case of structural child maltreatment, the bruises could have been caused at different times.
The University of Amsterdam had previously conducted research in this area using a camera that took a series of pictures to produce a full image. Demcon Focal decided to further research this topic using Imec’s new snapshot sensor, which records the complete spectral information in one go. Of course this is much more convenient for clinical practice. Demcon Focal built a research setup with Imec’s hyperspectral sensor at its core. This sensor can record 25 colors in the visible light spectrum. The more colors measured, the more accurate the distinction that can be made between hemoglobin and bilirubin.
The Dutch EXIST partner, Adimec, supplied a camera. Demcon Focal equipped it with its own lens system and built a setup with the maximum possible uniform lighting. The setup was used to take pictures of volunteers with bruises. The biggest challenge subsequently was to classify the images, that is, determine the relative quantities of hemoglobin and bilirubin in the bruise. Not an easy task, because the image quality (signal-noise ratio) of the Imec sensor was not terrific and the conditions, such as lighting, were subject to significant variations. The conclusion was that it is as yet impossible to demonstrate the added value of the new sensor for diagnosing bruises.
Thanks to the EXIST research, Demcon Focal has developed extensive expertise in hyperspectral imaging. A special algorithm was developed for the classification of images. This algorithm can be used on computers and has also been programmed in firmware (FPGA) for ultra-fast image processing. Opportunities appear to lie primarily in the invisible infrared spectrum for which no ordinary cameras are available. Focal is all set to provide industrial hyperspectral imaging applications.
This project has received funding from the ECSEL Joint Undertaking (JU) under grant agreement No 662222. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and Netherlands, Belgium, Germany, France, Austria, United Kingdom, Israel, Switzerland.
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