LED primary selection algorithms for simulation of CIE standard illuminants

Area of Science:

• Photometry and Color Science
• Optical Engineering
• Lighting Technology

Background:

• Accurate simulation of the CIE daylight series is essential for various applications.
• The spectral power distribution (SPD) of Light Emitting Diodes (LEDs) significantly impacts simulation fidelity.
• Existing methods for selecting LEDs for daylight simulation require optimization.

Purpose of the Study:

• To develop and evaluate algorithms for selecting optimal LEDs to simulate the CIE daylight series.
• To compare the performance of different selection algorithms under various standard illuminants.

Main Methods:

• Proposed three algorithms: "Equal" (wavelength spacing), "Gram" (Gram-Schmidt in spectral subspace), and "Ortho" (generalized Gram-Schmidt in illuminant subspace).
• Utilized 200 imaginary light primaries and 40 real LEDs for algorithm development and testing.
• Implemented and tested algorithms for CIE standard illuminants (D50, D55, D65, D75, C, A).

Main Results:

• Simulation performance generally improved with an increased number of selected LEDs or light primaries.
• "Gram" and "Ortho" algorithms demonstrated superior performance with real LEDs.
• The "Ortho" algorithm was identified as the best performer when using imaginary light primaries.

Conclusions:

• The choice of algorithm and the number of LEDs critically affect CIE daylight simulation accuracy.
• "Gram" and "Ortho" offer robust solutions for LED selection in practical daylight simulation.
• "Ortho" presents the most effective approach, especially in theoretical simulations with ideal light primaries.