The Yxy colour space parameters as novel signalling tools for digital imaging sensors in the analytical laboratory

Digital imaging devices can be promising, sensitive, and cost-effective chemical sensors for resource-limited settings. Three model colour reactions of iron were used and monitored using a simple platform consisting only of a camera, a cuvette, and a white paper diffuser. A desktop scanner and a mobile phone camera were also used as imaging devices. Captured images were analysed to obtain the RGB intensities (red, green, blue) and were further converted into the corresponding signals of the grayscale, CMY (cyan, magenta, yellow), XYZ (Y: luminance, XZ: chromaticity plane values) and Yxy colour spaces (Y: luminance, xy: chrominance values) analytical signals. The elegant procedure utilizing the Yxy signals surpassed those based on RGB, grayscale, CMY and tristimulus XYZ data regarding the calibration graph linearity and detection limit and compare well with those data obtained from a sophisticated spectrophotometer for assessing iron in complex environmental samples. The simplicity, sensitivity and cost effectiveness of the approach make it suitable for poorly equipped laboratories and locally deprived communities.