I need to know how to calculation CIE Color coordinates using UV-DRS measurement ? Is there any other way to find our CIE coordinates?
Are you wanting to measure the visible CIE coordinates? If so, I assume you also have a VIS detector and an integrating sphere.
A resource that might be of use for DRS and CIE is a chapter by ́ Torrent and Barron: http://www.uco.es/organiza/departamentos/decraf/pdf-edaf/DRS08.pdf
And another very good general reference site for CIE conversions is a site maintained by Bruce Lindbloom: www.brucelindbloom.com
Look-up the following references:
CIE 15:2004 Technical Report Colorimetry, 3rd Edition, ISBN 3 901 906 33 9
R.W.G. Hunt, M.R. Pointer, Measuring Colour, 4th Edition, Wiley, 2011
https://en.wikipedia.org/wiki/CIE_1931_color_space
https://en.wikipedia.org/wiki/Lab_color_space
First of all : what do you mean by "a compound", and do you have a reflectance spectrum or not ? If you have the spectrum it's easy : you just have to calculate a sum of products (The light source or "illuminant" spectrum times the reflectance times the human eye sensititvity aka "observer", all over the visible light wavelengths : you'll find the formulas in any color science textbook). But if you are trying to guess what the color of a compound would be (ie you don't have the measured reflectance) it becomes more complicated. If you are interested in "a pure chemical substance", the THEORETICAL SPECTRAL REFLECTANCE (not CIE color coordinates) depend on chemistry and cristallography, through the (spectral) refractive index and absorption coefficient of the compound (see any textbook about physics of colour). But knowing THEORETICAL REFLECTANCE of your "pure substance" is not enough if you are dealing with a real one, because reflectance of the compound is modified by the grains sizes and shapes if you deal with powers, by the film thickness if you deal with films, etc... that is it also depends on structure or texture. Then, CIE color coordinates depend on the viewing environment : to make your calculation you have to refer to a model of light source (which is called an "illuminant" in color science) and an observer (CIE coordinates deal with a model of the human eye sensititvity, which itself depends on the fraction of the field of vision that the object occupies). If you know all this, you have formulas in any color science textbook. So you see that the problem is not the calculation itself but the hypothsis you make before you calculate. The first step is probably getting the theoretical reflectance, then take care of the structure, then only compute CIE coordinates. Let me know if it helped. Olivier
If yuo just need xy (chromaticity coordinates) and you have the precise spectra, you just need to multiply the spectra with the colour matching function for the respective CIE standard observer you want to assume (CIE1931 most common, but not very precise, Judd-correct, or best Judd-Voss corrected). You can find colour matching functions for example here: http://www.cvrl.org/. You will get XYZ (Tristimulus Values), which you can convert to chromaticities by normalising them by intensities: x = X/(X+Y+Z) and y = Y/(X+Y+Z) (see https://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_xy_chromaticity_diagram_and_the_CIE_xyY_color_space).
I have the reflectance spectra of a thin film sample. Is it possible to calculate the CIE X and Y coordinates?
Thanks in advance.
https://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_xy_chromaticity_diagram_and_the_CIE_xyY_color_space
The ColorCalculator tool from OSRAM does this job pretty well.
( https://www.osram.us/cb/tools-and-resources/applications/led-colorcalculator/index.jsp )
The screen capture shows the example of a converted-phosphor green LED. It has the following chromaticity coordinates: Cx = 0.3286; Cy = 0.5598.
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