Accession Number : ADA529863


Title :   Calculating Correlated Color Temperatures Across the Entire Gamut of Daylight and Skylight Chromaticities


Descriptive Note : Journal article


Corporate Author : NAVAL ACADEMY ANNAPOLIS MD


Personal Author(s) : Hernandez-Andres, Javier ; Lee, Jr, Raymond L ; Romero, Javier


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a529863.pdf


Report Date : 20 Sep 1999


Pagination or Media Count : 8


Abstract : Natural outdoor illumination daily undergoes large changes in its correlated color temperature (CCT), yet existing equations for calculating CCT from chromaticity coordinates span only part of this range. To improve both the gamut and accuracy of these CCT calculations, we use chromaticities calculated from our measurements of nearly 7000 daylight and skylight spectra to test an equation that accurately maps CIE 1931 chromaticities x and y into CCT. We extend the work of McCamy [Color Res. Appl. 12, 285-287 (1992)] by using a chromaticity epicenter for CCT and the inverse slope of the line that connects it to x and y. With two epicenters for different CCT ranges, our simple equation is accurate across wide chromaticity and CCT ranges (3000-10(6) K) spanned by daylight and skylight.


Descriptors :   *CHROMATICITY , *COLOR TEMPERATURE , EQUATIONS , OUTDOOR , ILLUMINATION , REPRINTS , DAYLIGHT


Subject Categories : Optics
      Thermodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE