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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_SRGB_HPP
- #define ANTKEEPER_COLOR_SRGB_HPP
-
- #include "math/math.hpp"
- #include <cmath>
-
- namespace color {
-
- /// Functions which operate in the sRGB colorspace.
- namespace srgb {
-
- /**
- * Performs the sRGB Electro-Optical Transfer Function (EOTF), also known as the sRGB decoding function.
- *
- * @param v sRGB electrical signal (gamma-encoded sRGB).
- * @return Corresponding luminance of the signal (linear sRGB).
- */
- /// @{
- float eotf(float v);
- double eotf(double v);
- template <class T>
- math::vector3<T> eotf(const math::vector3<T>& v);
- /// @}
-
- /**
- * Performs the sRGB inverse Electro-Optical Transfer Function (EOTF), also known as the sRGB encoding function.
- *
- * @param l sRGB luminance (linear sRGB).
- * @return Corresponding electrical signal (gamma-encoded sRGB).
- */
- /// @{
- float eotf_inverse(float v);
- double eotf_inverse(double v);
- template <class T>
- math::vector3<T> eotf_inverse(const math::vector3<T>& l);
- /// @}
-
- /**
- * Calculates the luminance of a linear sRGB color.
- *
- * @param x Linear sRGB color.
- * @return return Luminance of @p x.
- */
- template <class T>
- T luminance(const math::vector3<T>& x);
-
- /**
- * Transforms a linear sRGB color into the ACEScg colorspace using the Bradford chromatic adaption transform.
- *
- * @param x Linear sRGB color.
- * @return ACEScg color.
- *
- * @see https://www.colour-science.org/apps/
- */
- template <class T>
- math::vector3<T> to_acescg(const math::vector3<T>& x);
-
- /**
- * Transforms a linear sRGB color into the CIE XYZ colorspace.
- *
- * @param x Linear sRGB color.
- * @return CIE XYZ color.
- */
- template <class T>
- math::vector3<T> to_xyz(const math::vector3<T>& x);
-
- inline float eotf(float v)
- {
- return (v < 0.04045f) ? (v / 12.92f) : std::pow((v + 0.055f) / 1.055f, 2.4f);
- }
-
- inline double eotf(double v)
- {
- return (v < 0.04045) ? (v / 12.92) : std::pow((v + 0.055) / 1.055, 2.4);
- }
-
- template <class T>
- math::vector3<T> eotf(const math::vector3<T>& v)
- {
- return math::vector3<T>
- {
- eotf(v[0]),
- eotf(v[1]),
- eotf(v[2])
- };
- }
-
- inline float eotf_inverse(float l)
- {
- return (l <= 0.0031308f) ? (l * 12.92f) : (std::pow(l, 1.0f / 2.4f) * 1.055f - 0.055f);
- }
-
- inline double eotf_inverse(double l)
- {
- return (l <= 0.0031308) ? (l * 12.92) : (std::pow(l, 1.0 / 2.4) * 1.055 - 0.055);
- }
-
- template <class T>
- math::vector3<T> eotf_inverse(const math::vector3<T>& l)
- {
- return math::vector3<T>
- {
- eotf_inverse(l[0]),
- eotf_inverse(l[1]),
- eotf_inverse(l[2])
- };
- }
-
- template <class T>
- T luminance(const math::vector3<T>& x)
- {
- static const math::vector3<T> luma = {0.212639005871510, 0.715168678767756, 0.072192315360734};
- return math::dot(x, luma);
- }
-
- template <class T>
- math::vector3<T> to_acescg(const math::vector3<T>& x)
- {
- static const math::matrix3<T> srgb_to_acescg
- {{
- {0.613132422390542, 0.070124380833917, 0.020587657528185},
- {0.339538015799666, 0.916394011313573, 0.109574571610682},
- {0.047416696048269, 0.013451523958235, 0.869785404035327}
- }};
-
- return srgb_to_acescg * x;
- }
-
- template <class T>
- math::vector3<T> to_xyz(const math::vector3<T>& x)
- {
- static const math::matrix3<T> srgb_to_xyz
- {{
- {0.412390799265959, 0.212639005871510, 0.019330818715592},
- {0.357584339383878, 0.715168678767756, 0.119194779794626},
- {0.180480788401834, 0.072192315360734, 0.950532152249661}
- }};
-
- return srgb_to_xyz * x;
- }
-
- } // namespace srgb
- } // namespace color
-
- #endif // ANTKEEPER_COLOR_SRGB_HPP
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