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Imaging Applications Use LEDs to Span the Spectrum

January 25, 2018

As more color cameras add infrared bands to their existing red, green, and blue channels, the machine vision market is seeing a resurgence in multispectral imaging solutions that once were only affordable by government institutions. Both multispectral and hyperspectral imaging applications require measuring the reflected energy from an object within bands of the electromagnetic spectrum. While multispectral vision systems may only sample between three and 10 different bands such as RBG and near infrared (NIR), hyperspectral systems may sample as many as 200 or more.

Since multispectral systems sample frequencies at narrower spectral bands, the images collected contain more data than multispectral images and thus can detect subtler differences between features of objects. However, larger data sets require specialized image processing and data analysis to turn spectral measurements into useable information.

Visual computing scientist Chloe LeGendre and her colleagues at the USC Institute for Creative Technologies (Playa Vista, California) have shown that, by analyzing 11 Luxeon LEDs from Lumileds (San Jose, California), as few as five LEDs of distinct spectra can be used for color-accurate multispectral lighting reproduction. These include red, green, and blue LEDs with narrow emission spectra, along with white and amber with broader spectra. To date, a number of companies have taken the approach of using multiple LEDs to produce broad-spectrum illumination products.

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