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- /*
- * Copyright (C) 2021 Christopher J. Howard
- *
- * This file is part of Antkeeper source code.
- *
- * Antkeeper source code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * Antkeeper source code is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
- */
-
- #ifndef ANTKEEPER_COLOR_CCT_HPP
- #define ANTKEEPER_COLOR_CCT_HPP
-
- #include "math/math.hpp"
- #include "ucs.hpp"
- #include "xyy.hpp"
-
- namespace color {
-
- /// Functions which operate on correlated color temperature (CCT).
- namespace cct {
-
- /**
- * Calculates CIE 1960 UCS colorspace chromaticity coordinates given a correlated color temperature using Krystek's algorithm.
- *
- * @param t Correlated color temperature, in Kelvin.
- * @return CIE 1960 UCS colorspace chromaticity coordinates.
- *
- * @see Krystek, M. (1985), An algorithm to calculate correlated colour temperature. Color Res. Appl., 10: 38-40.
- */
- template <class T>
- math::vector2<T> to_ucs(T t);
-
- /**
- * Calculates CIE xyY colorspace chromaticity coordinates given a correlated color temperature using Krystek's algorithm.
- *
- * @param t Correlated color temperature, in Kelvin.
- * @return CIE xyY color with `Y = 1`.
- */
- template <class T>
- math::vector3<T> to_xyy(T t);
-
- /**
- * Calculates CIE XYZ colorspace chromaticity coordinates given a correlated color temperature using Krystek's algorithm.
- *
- * @param t Correlated color temperature, in Kelvin.
- * @return CIE XYZ color with `Y = 1`.
- */
- template <class T>
- math::vector3<T> to_xyz(T t);
-
- template <class T>
- math::vector2<T> to_ucs(T t)
- {
- // Approximate the Planckian locus in CIE 1960 UCS colorspace (Krystek's algorithm)
- const T tt = t * t;
- return math::vector2<T>
- {
- (T(0.860117757) + T(1.54118254e-4) * t + T(1.28641212e-7) * tt) / (T(1.0) + T(8.42420235e-4) * t + T(7.08145163e-7) * tt),
- (T(0.317398726) + T(4.22806245e-5) * t + T(4.20481691e-8) * tt) / (T(1.0) - T(2.89741816e-5) * t + T(1.61456053e-7) * tt)
- };
- }
-
- template <class T>
- math::vector3<T> to_xyy(T t)
- {
- return ucs::to_xyy(to_ucs(t), T(1.0));
- }
-
- template <class T>
- math::vector3<T> to_xyz(T t)
- {
- return xyy::to_xyz(to_xyy(t));
- }
-
- } // namespace cct
- } // namespace color
-
- #endif // ANTKEEPER_COLOR_CCT_HPP
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