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33///////////////////////////////////////////////////////////////////////////
34
35
36#ifndef INCLUDED_IMF_CHROMATICITIES_H
37#define INCLUDED_IMF_CHROMATICITIES_H
38
39//-----------------------------------------------------------------------------
40//
41// CIE (x,y) chromaticities, and conversions between
42// RGB tiples and CIE XYZ tristimulus values.
43//
44//-----------------------------------------------------------------------------
45
46#include "ImathVec.h"
47#include "ImathMatrix.h"
48#include "ImfNamespace.h"
49#include "ImfExport.h"
50
51
52OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER
53
54
55struct Chromaticities
56{
57 //-----------------------------------------------
58 // The CIE x and y coordinates of the RGB triples
59 // (1,0,0), (0,1,0), (0,0,1) and (1,1,1).
60 //-----------------------------------------------
61
62 IMATH_NAMESPACE::V2f red;
63 IMATH_NAMESPACE::V2f green;
64 IMATH_NAMESPACE::V2f blue;
65 IMATH_NAMESPACE::V2f white;
66
67 //--------------------------------------------
68 // Default constructor produces chromaticities
69 // according to Rec. ITU-R BT.709-3
70 //--------------------------------------------
71
72 IMF_EXPORT
73 Chromaticities (const IMATH_NAMESPACE::V2f &red = IMATH_NAMESPACE::V2f (0.6400f, 0.3300f),
74 const IMATH_NAMESPACE::V2f &green = IMATH_NAMESPACE::V2f (0.3000f, 0.6000f),
75 const IMATH_NAMESPACE::V2f &blue = IMATH_NAMESPACE::V2f (0.1500f, 0.0600f),
76 const IMATH_NAMESPACE::V2f &white = IMATH_NAMESPACE::V2f (0.3127f, 0.3290f));
77
78
79 //---------
80 // Equality
81 //---------
82
83 IMF_EXPORT
84 bool operator == (const Chromaticities &v) const;
85 IMF_EXPORT
86 bool operator != (const Chromaticities &v) const;
87};
88
89
90//
91// Conversions between RGB and CIE XYZ
92//
93// RGB to XYZ:
94//
95// Given a set of chromaticities, c, and the luminance, Y, of the RGB
96// triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so
97// that multiplying an RGB value, v, with M produces an equivalent
98// XYZ value, w. (w == v * M)
99//
100// If we define that
101//
102// (Xr, Yr, Zr) == (1, 0, 0) * M
103// (Xg, Yg, Zg) == (0, 1, 0) * M
104// (Xb, Yb, Zb) == (0, 0, 1) * M
105// (Xw, Yw, Zw) == (1, 1, 1) * M,
106//
107// then the following statements are true:
108//
109// Xr / (Xr + Yr + Zr) == c.red.x
110// Yr / (Xr + Yr + Zr) == c.red.y
111//
112// Xg / (Xg + Yg + Zg) == c.red.x
113// Yg / (Xg + Yg + Zg) == c.red.y
114//
115// Xb / (Xb + Yb + Zb) == c.red.x
116// Yb / (Xb + Yb + Zb) == c.red.y
117//
118// Xw / (Xw + Yw + Zw) == c.red.x
119// Yw / (Xw + Yw + Zw) == c.red.y
120//
121// Yw == Y.
122//
123// XYZ to RGB:
124//
125// XYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse().
126//
127
128IMF_EXPORT IMATH_NAMESPACE::M44f RGBtoXYZ (const Chromaticities &chroma, float Y);
129IMF_EXPORT IMATH_NAMESPACE::M44f XYZtoRGB (const Chromaticities &chroma, float Y);
130
131
132OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT
133
134#endif
135

source code of include/OpenEXR/ImfChromaticities.h