///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2003, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
//
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///////////////////////////////////////////////////////////////////////////
#ifndef INCLUDED_IMF_CHROMATICITIES_H
#define INCLUDED_IMF_CHROMATICITIES_H
//-----------------------------------------------------------------------------
//
// CIE (x,y) chromaticities, and conversions between
// RGB tiples and CIE XYZ tristimulus values.
//
//-----------------------------------------------------------------------------
#include "ImathVec.h"
#include "ImathMatrix.h"
namespace Imf {
struct Chromaticities
{
//-----------------------------------------------
// The CIE x and y coordinates of the RGB triples
// (1,0,0), (0,1,0), (0,0,1) and (1,1,1).
//-----------------------------------------------
Imath::V2f red;
Imath::V2f green;
Imath::V2f blue;
Imath::V2f white;
//--------------------------------------------
// Default constructor produces chromaticities
// according to Rec. ITU-R BT.709-3
//--------------------------------------------
Chromaticities (const Imath::V2f &red = Imath::V2f (0.6400f, 0.3300f),
const Imath::V2f &green = Imath::V2f (0.3000f, 0.6000f),
const Imath::V2f &blue = Imath::V2f (0.1500f, 0.0600f),
const Imath::V2f &white = Imath::V2f (0.3127f, 0.3290f));
};
//
// Conversions between RGB and CIE XYZ
//
// RGB to XYZ:
//
// Given a set of chromaticities, c, and the luminance, Y, of the RGB
// triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so
// that multiplying an RGB value, v, with M produces an equivalent
// XYZ value, w. (w == v * M)
//
// If we define that
//
// (Xr, Yr, Zr) == (1, 0, 0) * M
// (Xg, Yg, Zg) == (0, 1, 0) * M
// (Xb, Yb, Zb) == (0, 0, 1) * M
// (Xw, Yw, Zw) == (1, 1, 1) * M,
//
// then the following statements are true:
//
// Xr / (Xr + Yr + Zr) == c.red.x
// Yr / (Xr + Yr + Zr) == c.red.y
//
// Xg / (Xg + Yg + Zg) == c.red.x
// Yg / (Xg + Yg + Zg) == c.red.y
//
// Xb / (Xb + Yb + Zb) == c.red.x
// Yb / (Xb + Yb + Zb) == c.red.y
//
// Xw / (Xw + Yw + Zw) == c.red.x
// Yw / (Xw + Yw + Zw) == c.red.y
//
// Yw == Y.
//
// XYZ to RGB:
//
// YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse().
//
Imath::M44f RGBtoXYZ (const Chromaticities chroma, float Y);
Imath::M44f XYZtoRGB (const Chromaticities chroma, float Y);
} // namespace Imf
#endif