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3// Copyright (c) 2003, Industrial Light & Magic, a division of Lucas
4// Digital Ltd. LLC
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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 IMF_EXPORT 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 Chromaticities (const IMATH_NAMESPACE::V2f &red = IMATH_NAMESPACE::V2f (0.6400f, 0.3300f),
73 const IMATH_NAMESPACE::V2f &green = IMATH_NAMESPACE::V2f (0.3000f, 0.6000f),
74 const IMATH_NAMESPACE::V2f &blue = IMATH_NAMESPACE::V2f (0.1500f, 0.0600f),
75 const IMATH_NAMESPACE::V2f &white = IMATH_NAMESPACE::V2f (0.3127f, 0.3290f));
76
77
78 //---------
79 // Equality
80 //---------
81
82 bool operator == (const Chromaticities &v) const;
83 bool operator != (const Chromaticities &v) const;
84};
85
86
87//
88// Conversions between RGB and CIE XYZ
89//
90// RGB to XYZ:
91//
92// Given a set of chromaticities, c, and the luminance, Y, of the RGB
93// triple (1,1,1), or "white", RGBtoXYZ(c,Y) computes a matrix, M, so
94// that multiplying an RGB value, v, with M produces an equivalent
95// XYZ value, w. (w == v * M)
96//
97// If we define that
98//
99// (Xr, Yr, Zr) == (1, 0, 0) * M
100// (Xg, Yg, Zg) == (0, 1, 0) * M
101// (Xb, Yb, Zb) == (0, 0, 1) * M
102// (Xw, Yw, Zw) == (1, 1, 1) * M,
103//
104// then the following statements are true:
105//
106// Xr / (Xr + Yr + Zr) == c.red.x
107// Yr / (Xr + Yr + Zr) == c.red.y
108//
109// Xg / (Xg + Yg + Zg) == c.red.x
110// Yg / (Xg + Yg + Zg) == c.red.y
111//
112// Xb / (Xb + Yb + Zb) == c.red.x
113// Yb / (Xb + Yb + Zb) == c.red.y
114//
115// Xw / (Xw + Yw + Zw) == c.red.x
116// Yw / (Xw + Yw + Zw) == c.red.y
117//
118// Yw == Y.
119//
120// XYZ to RGB:
121//
122// YYZtoRGB(c,Y) returns RGBtoXYZ(c,Y).inverse().
123//
124
125IMF_EXPORT IMATH_NAMESPACE::M44f RGBtoXYZ (const Chromaticities chroma, float Y);
126IMF_EXPORT IMATH_NAMESPACE::M44f XYZtoRGB (const Chromaticities chroma, float Y);
127
128
129OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT
130
131#endif
132