LED primary selection algorithms for simulation of CIE standard illuminants

Abstract

Although mixture of LEDs is being considered as a simulator of the CIE daylight series, the performance of the simulations is highly dependent on the SPD of the selected LEDs. An algorithm for selection of the best LEDs for simulation of the CIE daylight series is helpful in this regard. To address this problem, using 200 imaginary light primaries and 40 real LEDs, three algorithms based on concepts of equally spacing of wavelength range (“Equal”), Gram Schmidt orthogonalization in LEDs/light primaries spectral subspace (“Gram”) and the generalization of Gram Schmidt orthogonalization in the LEDs/light primaries projections onto the illuminants subspace (“Ortho”) were proposed and studied. Algorithms, in simulation and reality, were implemented for the CIE standard illuminants of D50, D55, D65 and D75, C and A. The results showed that the performance of the proposed algorithms generally increase with the higher number of selected LEDs/light primaries, while for the LEDs “Gram” and “Ortho” methods showed superior performance, simulations on the imaginary light primaries showed “Ortho” could be considered as the best algorithm.