colourSpace.h

   1 /* ***** BEGIN LICENSE BLOCK *****
   2  *
   3  * $Id$
   4  *
   5  * The MIT License
   6  *
   7  * Copyright (c) 2008 BBC Research
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
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  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
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  17  * all copies or substantial portions of the Software.
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  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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  25  * THE SOFTWARE.
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  27  * ***** END LICENSE BLOCK ***** */
  28
  29 #ifndef __COLOURSPACE_H
  30 #define __COLOURSPACE_H
  31
  32 #include "rawFrame.h"
  33
  34 // USEFUL INFORMATION
  35 // THERE ARE TWO COLOUR SYSTEMS WE ARE INTERESTED IN, 'SDTV' and 'HDTV', WHICH
  36 // COVER ALL REAL APPLICATIONS
  37
  38 //SDTV :-
  39 //ITU-R BT 601
  40 //ITU-R BT 470, PAL system B/G
  41 //SMPTE 170M, NTSC
  42 //SMPTE 293M, 720x483 59.94P
  43 //
  44 //Ey  =  0.299Er + 0.587Eg + 0.114Eb
  45
  46 //HDTV :-
  47 //ITU-R BT 709 (1125/60/2:1 only)
  48 //ITU-R BT 1361 Worldwide Unified HDTV
  49 //SMPTE 274M 1920x1080 HDTV
  50 //SMPTE 296M 1280x720 HDTV
  51 //
  52 //Ey  =  0.2126Er + 0.7152Eg + 0.0722Eb
  53
  54 //For converting RGB to YCbCr
  55 //
  56 // Ey = Kg.Eg + Kb.Eb + Kr.Er
  57 // and
  58 // Kg + Kb + Kr = 1
  59 //
  60 // Ecb = (Eb-Ey) / (2(1-Kb))
  61 // Ecr = (Er-Ey) / (2(1-Kr))
  62
  63 //For converting YCbCr to RGB
  64 //
  65 // Er = Ey + 2(1-Kr)Ecr
  66 // Eg = Ey - (2(1-Kb)Kb.Ecb)/Kg - (2(1-Kr)Kr.Ecr)/Kg
  67 // Eb = Ey + 2(1-Kb)Ecb
  68
  69 //This class builds the colour matrix using the equations above from Kr, Kg, Kb
  70
  71 class ColourSpace {
  72 public:
  73
  74         enum MatrixType {SDTVtoYUV, SDTVtoRGB, HDTVtoYUV, HDTVtoRGB};
  75
  76         ColourSpace(int inWidth, int inHeight, RawFrame::Chroma destChroma) :
  77                 _width(inWidth), _height(inHeight), _converted(inWidth, inHeight,
  78                                                                destChroma)
  79         {
  80                 //construct matrices
  81                 buildYUVMatrix(matrices[SDTVtoYUV], (float)0.299, (float)0.587,
  82                                (float)0.114);
  83                 buildRGBMatrix(matrices[SDTVtoRGB], (float)0.299, (float)0.587,
  84                                (float)0.114);
  85                 buildYUVMatrix(matrices[HDTVtoYUV], (float)0.2126, (float)0.7152,
  86                                (float)0.0722);
  87                 buildRGBMatrix(matrices[HDTVtoRGB], (float)0.2126, (float)0.7152,
  88                                (float)0.0722);
  89         }
  90         ;
  91
  92         //reference matrix coefficients generated from Kr, Kg, Kb
  93         typedef struct _ColourMatrix {
  94                 double a, b, c;
  95                 double d, e, f;
  96                 double g, h, i;
  97         } ColourMatrix;
  98
  99         //integer matrix coefficients used for the actual processing
 100         //these may have been scaled to adjust number ranges during conversion
 101         typedef struct _ColourMatrixInt {
 102                 int a, b, c;
 103                 int d, e, f;
 104                 int g, h, i;
 105         } ColourMatrixInt;
 106
 107         const RawFrame& process(const RawFrame &src, const MatrixType type,
 108                                 const bool scaledRGB, const bool YOnly,
 109                                 const int depth);
 110         void process_ext(const RawFrame &src, RawFrame& dest,
 111                          const MatrixType type, const bool scaledRGB,
 112                          const bool YOnly, const int depth);
 113
 114 protected:
 115         void buildRGBMatrix(ColourMatrix &matrix, const float Kr, const float Kg,
 116                             const float Kb);
 117         void buildYUVMatrix(ColourMatrix &matrix, const float Kr, const float Kg,
 118                             const float Kb);
 119
 120         /* input size */
 121         const int _width;
 122         const int _height;
 123
 124         /* colour matrices */
 125         ColourMatrix matrices[4];
 126
 127         /* output */
 128         RawFrame _converted;
 129 };
 130
 131 #endif