![]() It is worthy to mention that, the CIE (Commission Internationale de l'Eclairage, International Commission on Illumination) has classified the RGB, CMY, YXZ, and Yxy spaces as non-uniform colour spaces, where at constant luminance, the colour differences represented by equal distances are not perceived, by the human eye, as being equal. The free online Colormine converter is very simple and was adopted in this work. † However, some programs perform these conversions at a click of a button. The mathematical conversion of RGB intensities into the corresponding parameters of other colour spaces is well documented 27–30 A brief introduction to the aforementioned colour spaces and their inter-conversions is given in the ESI. 6,13,16,17,25,26 However, some other excellent papers on the topic have been undoubtedly missed and can be found in excellent reviews of the topic. Images have been captured using digital cameras, 9,14,18,24 mobile phone cameras, 4,7,12,15,17,19,23 web cams, 10,11 or computer scanners. The RGB intensities, 1–10 the RGB absorbance ( A R, A G, A B, A RGB), 11–14 the normalized I G/ I R ratio, 15 the cyan, magenta, and yellow (CMY) intensities, 16–19 the tristimulus XYZ parameters, 20–22 the greyscale intensity, 23,24 and the inverted 8 bit greyscale intensity 25,26 have been used as analytical signals in DIBA. DIBA relies on a colour change, wherein the analyte reacts with a chromogenic reagent to give a coloured product, the digital images of which are analysed to obtain the red, green and blue (RGB) intensity values ( I R, I G, I B, and I RGB). Therefore, methods of digital image-based analysis (DIBA) are suggested as simple and low-cost alternatives. However, bulky size and relatively high cost are common disadvantages of many research grade spectrometers. Spectrochemical methods utilizing the light absorbed by (or emitted from) a sample are very popular in quantitative chemical analysis. The simplicity, sensitivity and cost effectiveness of the approach make it suitable for poorly equipped laboratories and locally deprived communities. 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. 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. A desktop scanner and a mobile phone camera were also used as imaging devices. ![]() 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. Increasing the luminosity moves you towards white, decreasing it moves you towards black.Digital imaging devices can be promising, sensitive, and cost-effective chemical sensors for resource-limited settings. Reduce the saturation and you move towards gray. Pick a Hue from 0 to 360 and with saturation at 100 and luminosity at 50 and you'll have the purest form of that color. ![]() Without a decent HSL color picker, it's difficult to understand. Now, with CSS3 we can use HSL which is actually quite different than HSB. In graphics software I pick colors in HSB (Hue, Saturation, Brightness) because it feels more natural to work with than RGB or CMYK. Look at that in hex, #2C1D07 to #DDCFBB, or in rgb, rgb(44, 29, 7) to rgb(221, 207, 187), and the relationship between colors isn't evident in any meaningful way. Give this brown color, hsl(36, 73%, 10%), it's clear that if we desaturate 40 steps and lighten 70 steps we get hsl(36, 33%, 80%), a cream color. HSL (Hue, Saturation, Luminosity) allows us to describe meaningful relationships between colors.
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