chromatic_adaptation.h

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#pragma once
 
// Chromatic adaptation between white points (P6, #4040).
//
// B7 makes Bradford the normative CAT. The whole adaptation collapses to one
// 3x3 matrix, built when a profile is bound, so nothing iterative or
// trigonometric runs per pixel -- and folding it into the source matrix makes
// it free, since the two then cost a single multiply together.
 
#include "fl/gfx/color_profile.h"
#include "fl/gfx/source_xyz.h"
#include "fl/stl/int.h"
#include "fl/stl/noexcept.h"
 
namespace fl {
namespace detail {

extern const float kBradford[3][3];
extern const float kBradfordInverse[3][3];
extern const i32 kBradfordQ16[3][3];
extern const i32 kBradfordInverseQ16[3][3];
 
} // namespace detail

struct AdaptationMatrixQ16 {
    i32 m[3][3];
};

bool buildBradfordMatrixQ16(Chromaticity source_white,
                            Chromaticity destination_white,
                            AdaptationMatrixQ16* out) FL_NO_EXCEPT;

void adaptXyzQ16(const AdaptationMatrixQ16& matrix, const i32 (&xyz)[3],
                 i32 (&out_xyz)[3]) FL_NO_EXCEPT;

void foldAdaptationIntoSourceMatrix(const AdaptationMatrixQ16& adaptation,
                                    SourceMatrixQ16* source) FL_NO_EXCEPT;
 
}  // namespace fl