Learn More
The average spectral power distribution of a set of measured daylight spectra, E(av)(lambda), is used for preliminary screening to select optimal sensor sets for daylight recovery. Spectra quite different from E(av)(lambda) are applied to the screened sets to obtain minimum total spectral error, which is closely related to recovery metrics but not to the(More)
This paper presents an efficient algorithm for computing the two-dimensional discrete cosine transform (2-D DCT) of size p<sup>r</sup> &#x00D7; p<sup>r</sup>, where p is a prime. The algorithm decomposes the 2-D DCT outputs into three parts: the first part contains outputs whose indices are both multiples of p and forms a 2-D DCT of size p<sup>r-1</sup>(More)
Algorithms for selecting LEDs to imitate a group of daylight spectra, instead of fixed-spectrum lighting, are based on minimizing two indices. The first index related to the LEDs only is minimized for determining LED candidates. Minimizing the second index obtained by applying the daylight spectra to the candidates achieves a minimax solution. The sum of(More)
Two useful discrete Fourier preprocessing transforms (DFPTs), say, class 1 and class 2, are applied to the binary phase-only filter. The class-1 DFPT is very close to the discrete Fourier transform (DFT); therefore it preserves the properties similar to those for the DFT. The Class-2 DFPT's are location sensitive and are able to recognize the(More)
A new method of creating a source model of a phosphor-converted white LED is demonstrated. It is based on a simple phosphor model, of which some key parameters have been obtained from measuring the near-field chromatic and luminance characteristics of a complete LED. The accuracy of the model is verified by measurements and simulations on an LED with a ball(More)
  • 1