COLOUR IMAGING g


while there are two lines, there is a gap between those lines. ‘Tis also results in the colour fringes,’ he said, ‘which are less than with the trilinear, but still there.’ Te prism approach, however, because


of its single optical access, means that it is less relevant whether there is vibration or not, because there is the same effect in all channels. ‘Tere is no need for any compensation there,’ explained Prayagi. Colour imaging, in the form of Bayer


mosaic imaging, was developed in 1974, when US scientist Bryce Bayer invented the Bayer filter while working for Kodak. However, Prayagi said, the resolution at that time was very low. ‘Te real resolution of blue, for example, is not exactly all the pixels on the sensor, it is probably only one third.’ Tis problem was more recently overcome using the prism approach. Has colour imaging now reached its


peak performance, or can it be developed further, opening up more new and exciting applications? Te latter thinks Prayagi. ‘It can get


better, but mainly in terms of multi-spectral imaging. Te advantage we have with the prism approach is that, if you want to have a really special colour reproduction, for example, with sorting fruit, you need to have a certain waveband that is much more narrow than a standard sensor waveband.’ A recent launch from the company has


been designed for just this purpose. Te Flex-Eye configurator tool can be used by customers as a multi-spectral solution. ‘You can define special wavebands,’ said


Prayagi, ‘that cannot be used for a standard RGB camera. ‘Te result is that you can have special


responses in RGB, and also near-infrared imaging combined, which are customised to fit a specific application.’


Digital colour imaging can be used for disease diagnostics and monitoring progression of a disease


Colour imaging via an app Sensor solutions manufacturer Sick has also seen an increase in demand for colour imaging. It has developed a colour inspection and sorting app, as part of its SensorApps range for simple machine vision setup. Among its applications, the app can be


used to check that goods, assemblies or packs on a conveyor belt are the right size or colour. It can count objects with different sizes and colours, as well as validate the correct colour or colour gradations, for example of baked goods, or automotive components in an assembly. Objects with anomalies, such as the wrong colour or size, can be identified for rejection, and the integrity and completeness of secondary packaging can be confirmed. It is designed to work with the company’s


access that is reflected from the object, and then we split the light inside the camera’


SIM4000, SIM1012 or SIM1004 cameras. Te solution was developed with ease-


of-use in mind. Te object colour can be matched by using the colour scale or by simply inputting the colour pigment. Object sizes are easily defined by minimum and maximum pixel values.


Multiple use cases Te potential applications for colour imaging could be anything from intelligent farming, where it can help to monitor plant health and growth, to inspecting lice on salmon skin for fish farmers, to medical and surgical guidance. Prayagi explained: ‘One use is for early detection of tumours, where the big challenge is to be as accurate as possible in surgery. So, the cut on the body needs to be as small as possible and this can only be done if it is accurate, so we know what the trouble area is.’ In this scenario, the patient is injected


with indocyanine green (ICG) dye, which clings on to the tumours, allowing them to be optically identified using prism-based cameras. Te number and type of applications


Moving fruit and vegetables can cause problems when using trilinear cameras that cannot compensate for high-speed movement


22 IMAGING AND MACHINE VISION EUROPE OCTOBER/NOVEMBER 2020


for colour imaging is growing, according to Prayagi, such as pharmaceuticals and cosmetics, for identifying defects in drugs or their packaging, as well as electronics, meat and poultry inspection, and inspecting currency and passports. O


@imveurope | www.imveurope.com ‘Tere is a single optical


JAI


JAI


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