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Colorimetric Accuracies and Concerns in Spectroradiometry of LEDs



C Jones, Yoshi Ohno


LEDs are narrow-band emission sources and present special problems in colorimetric characterization. Chromaticity space is mapped using Gaussian spectral models to represent narrow-band emission sources. The Gaussian maps show that the spectral regions are distorted and non-uniform. These maps predict that the measured chromaticity coordinates and dominant wavelength are sensitive to spectral width and spectral shape. To investigate such effects on colorimetric accuracies of spectroradiometric measurements for LEDs, computer simulations were conducted, evaluating the effects of bandpass and other parameters of a spectroradiometer on the measured chromaticity and dominant wavelength of LEDs. A Gaussian function was used to mimic LED spectra with varied spectral widths at varied peak wavelengths over the visible region. The results indicate that errors caused by a maximum bandpass of 5 nm (FWHM) of a spectroradiometer will be less than 0.002 in x, y, and 0.2 nm in dominant wavelength, and can be accepted for most practical measurements of LEDs. The scanning interval (1 nm to 10 nm) was found not critical for LEDs with spectral widths of 20 nm (FWHM) or more.
Proceedings Title
Proceedings of CIE Symposium '99, 75 Years of CIE Photometry
Conference Dates
September 10-October 2, 1999
Conference Location
Budapest, 1, HU
Conference Title
CIE Expert Symposium


chromaticity diagram, colorimetry, dominant wavelength, gaussian models, LEDs, spectral width, spectroadiometry, spectroradiometer


Jones, C. and Ohno, Y. (1999), Colorimetric Accuracies and Concerns in Spectroradiometry of LEDs, Proceedings of CIE Symposium '99, 75 Years of CIE Photometry, Budapest, 1, HU (Accessed May 18, 2024)


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Created October 1, 1999, Updated October 12, 2021