Although the software that came with the vis-NIR has a colorimetry option, you have to manually record soil color (RGB, CIELAB) for each spectra. I have vis-NIR spectra for over 900 soil samples, and took triplicate scans. It would be awesome if there was an R code I could use to get soil color quickly. Thanks!
Dear Jennifer, I would like to gently lead you away from R-codes and introduce you to CIE colorimetry. You task of converting your spectral curves into internationally agreed CIELAB co-ordinates may be resolved into a fully automated process using the CIE Standard Observer colorimetry. A full account of this is given by Janos Shanda in Chapter 3 of his book “understanding the CIE system” which is available on-line. See also the (perhaps easier to read) book ‘Billmeyer and Saltzman’s Principle of Color Technology ‘ by Roy S Berns, which is also available on line.
In brief, the CIE Colorimetry Committee specified a series of visual Standard Observer and Standard Illuminant models based on well-founded practical experiments, whose product is in each case is a set of spectral weighting coefficients that specify visual intensity. Your calculation then involves multiplying the spectral power values by both these weighting coefficients and summing the result three dimensionally over wavelength. The resulting CIE XYZ colour Identity co-ordinates are then mapped onto CIELAB values in order to redistribute them more evenly in colour space.
Dear Jennifer, I would like to gently lead you away from R-codes and introduce you to CIE colorimetry. You task of converting your spectral curves into internationally agreed CIELAB co-ordinates may be resolved into a fully automated process using the CIE Standard Observer colorimetry. A full account of this is given by Janos Shanda in Chapter 3 of his book “understanding the CIE system” which is available on-line. See also the (perhaps easier to read) book ‘Billmeyer and Saltzman’s Principle of Color Technology ‘ by Roy S Berns, which is also available on line.
In brief, the CIE Colorimetry Committee specified a series of visual Standard Observer and Standard Illuminant models based on well-founded practical experiments, whose product is in each case is a set of spectral weighting coefficients that specify visual intensity. Your calculation then involves multiplying the spectral power values by both these weighting coefficients and summing the result three dimensionally over wavelength. The resulting CIE XYZ colour Identity co-ordinates are then mapped onto CIELAB values in order to redistribute them more evenly in colour space.
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