In this work, the authors aim to present a compact low-cost and portable spectral imaging system for general purposes. The developed system provides information that can be used for a fast in situ identification and classification of samples based on the analysis of captured images. The connectivity of the instrument allows a deeper analysis of the images in an external computer.
The wavelength selection of the system is carried out by light multiplexing through a light-emitting diode panel where eight wavelengths covering the spectrum from ultraviolet (UV) to near-infrared region (NIR) have been included. The image sensor used is a red green blue – infrared (RGB-IR) micro-camera controlled by a Raspberry Pi board where a basic image processing algorithm has been programmed. It allows the visualization in an integrated display of the reflectance and the histogram of the images at each wavelength, including UV and NIRs.
The prototype has been tested by analyzing several samples in a variety of applications such as detection of damaged, over-ripe and sprayed fruit, classification of different type of plastic materials and determination of properties of water.
The designed system presents some advantages as being non-expensive and portable in comparison to other multispectral imaging systems. The low-cost and size of the camera module connected to the Raspberry Pi provides a compact instrument for general purposes.
This work was supported by project CTQ2013-44545-R from the Ministry of Economy and Competitiveness (Spain) and Junta de Andalucía (Proyecto de Excelencia P10-FQM-5974). These projects were partially supported by European Regional Development Funds (ERDF).
Lopez-Ruiz, N., Granados-Ortega, F., Carvajal, M.A. and Martinez-Olmos, A. (2017), "Portable multispectral imaging system based on Raspberry Pi", Sensor Review, Vol. 37 No. 3, pp. 322-329. https://doi.org/10.1108/SR-12-2016-0276
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