color.h

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/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
*                                                                _   O  _   *
* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
*                                                                    \      *
* All rights reserved.                                                      *
*                                                                           *
* This program is free software; you can redistribute it and/or modify      *
* it under the terms of the GNU General Public License as published by      *
* the Free Software Foundation; either version 2 of the License, or         *
* (at your option) any later version.                                       *
*                                                                           *
* This program is distributed in the hope that it will be useful,           *
* but WITHOUT ANY WARRANTY; without even the implied warranty of            *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt)          *
* for more details.                                                         *
*                                                                           *
****************************************************************************/

#ifndef __VCG_TRI_UPDATE_COLOR
#define __VCG_TRI_UPDATE_COLOR

#include <limits>
#include <math.h>
#include <time.h>
#include <vcg/space/color4.h>
#include <vcg/math/histogram.h>
#include <vcg/math/perlin_noise.h>
#include <vcg/math/random_generator.h>
#include <vcg/complex/algorithms/clean.h>
#include <vcg/complex/algorithms/stat.h>

namespace vcg {
namespace tri {

template <class MeshType>
class UpdateColor
{
public:
  typedef typename MeshType::VertexType     VertexType;
  typedef typename MeshType::VertexPointer  VertexPointer;
  typedef typename MeshType::VertexIterator VertexIterator;
  typedef typename MeshType::FaceType       FaceType;
  typedef typename MeshType::FacePointer    FacePointer;
  typedef typename MeshType::FaceIterator   FaceIterator;
  typedef typename MeshType::EdgeIterator   EdgeIterator;

  typedef typename MeshType::ScalarType     ScalarType;
  typedef typename MeshType::CoordType      CoordType;

  class ColorAvgInfo
  {
  public:
    unsigned int r;
    unsigned int g;
    unsigned int b;
    unsigned int a;
    int cnt;
  };

  static int PerVertexConstant(MeshType &m, Color4b vs=Color4b::White,bool selected=false)
  {
    RequirePerVertexColor(m);

    int cnt=0;
    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi)
      if(!(*vi).IsD()){
        if(!selected || (*vi).IsS())
        {
          (*vi).C() = vs;
          ++cnt;
        }
      }
    return cnt;
  }

  static int PerFaceConstant(MeshType &m, Color4b vs=Color4b::White,bool selected=false)
  {
    RequirePerFaceColor(m);
    int cnt=0;
    for(FaceIterator fi=m.face.begin();fi!=m.face.end();++fi)
      if(!(*fi).IsD()){
        if(!selected || (*fi).IsS())
        {
          (*fi).C() = vs;
          ++cnt;
        }
      }
    return cnt;
  }

  static void PerVertexFromFace( MeshType &m)
  {
    RequirePerFaceColor(m);
    RequirePerVertexColor(m);

    ColorAvgInfo csi;
    csi.r=0; csi.g=0; csi.b=0; csi.cnt=0;
    SimpleTempData<typename MeshType::VertContainer, ColorAvgInfo> TD(m.vert,csi);

    FaceIterator fi;
    for(fi=m.face.begin();fi!=m.face.end();++fi)
      if(!(*fi).IsD())
        for(int j=0;j<3;++j)
        {
          TD[(*fi).V(j)].r+=(*fi).C()[0];
          TD[(*fi).V(j)].g+=(*fi).C()[1];
          TD[(*fi).V(j)].b+=(*fi).C()[2];
          TD[(*fi).V(j)].a+=(*fi).C()[3];
          ++TD[(*fi).V(j)].cnt;
        }

    VertexIterator vi;
    for(vi=m.vert.begin();vi!=m.vert.end();++vi)
      if(!(*vi).IsD() && TD[*vi].cnt>0 )
      {
        (*vi).C()[0] = TD[*vi].r / TD[*vi].cnt;
        (*vi).C()[1] = TD[*vi].g / TD[*vi].cnt;
        (*vi).C()[2] = TD[*vi].b / TD[*vi].cnt;
        (*vi).C()[3] = TD[*vi].a / TD[*vi].cnt;
      }
  }

  static void PerFaceFromVertex( MeshType &m)
  {
    RequirePerFaceColor(m);
    RequirePerVertexColor(m);

    FaceIterator fi;
    for(fi=m.face.begin();fi!=m.face.end();++fi) if(!(*fi).IsD())
    {
      Color4f avg = (Color4f::Construct((*fi).V(0)->C()) +
                     Color4f::Construct((*fi).V(1)->C()) +
                     Color4f::Construct((*fi).V(2)->C()) )/ 3.0;
      (*fi).C().Import(avg);
    }
  }

  static void PerVertexQualityRamp(MeshType &m, float minq=0, float maxq=0)
  {
    RequirePerVertexQuality(m);
    RequirePerVertexColor(m);

    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerVertexQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi)
          if(!(*vi).IsD())
              (*vi).C().SetColorRamp(minq,maxq,(*vi).Q());
  }

  
  static void PerVertexQualityRampParula(MeshType &m, float minq=0, float maxq=0)
  {
    RequirePerVertexQuality(m);
    RequirePerVertexColor(m);

    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerVertexQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi)
          if(!(*vi).IsD())
              (*vi).C().SetColorRampParula(minq,maxq,(*vi).Q());
  }
  
  static void PerFaceQualityRamp(MeshType &m, float minq=0, float maxq=0, bool selected=false)
  {
    RequirePerFaceColor(m);
    RequirePerFaceQuality(m);

    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerFaceQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(FaceIterator fi=m.face.begin();fi!=m.face.end();++fi) if(!(*fi).IsD())
      if(!selected || (*fi).IsS())
        (*fi).C().SetColorRamp(minq,maxq,(*fi).Q());
  }

  static void PerEdgeQualityRamp(MeshType &m, float minq=0, float maxq=0, bool selected=false)
  {
    RequirePerEdgeColor(m);
    RequirePerEdgeQuality(m);

    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerEdgeQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(EdgeIterator ei=m.edge.begin();ei!=m.edge.end();++ei) if(!(*ei).IsD())
      if(!selected || (*ei).IsS())
        (*ei).C().SetColorRamp(minq,maxq,(*ei).Q());
  }

  static void PerVertexQualityGray(MeshType &m,  float minq,  float maxq)
  {
    RequirePerVertexColor(m);
    RequirePerVertexQuality(m);
    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerVertexQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(VertexIterator vi=m.vert.begin();vi!=m.vert.end();++vi)
          if(!(*vi).IsD())
              (*vi).C().SetGrayShade( ((*vi).Q()-minq)/(maxq-minq));
  }

  static void PerFaceQualityGray(MeshType &m, float minq=0, float maxq=0)
  {
    RequirePerFaceColor(m);
    RequirePerFaceQuality(m);

    if(minq==maxq)
    {
      std::pair<float,float> minmax = Stat<MeshType>::ComputePerFaceQualityMinMax(m);
      minq=minmax.first;
      maxq=minmax.second;
    }
    for(FaceIterator fi=m.face.begin();fi!=m.face.end();++fi) if(!(*fi).IsD())
          (*fi).C().SetGrayShade( ((*fi).Q()-minq)/(maxq-minq));
  }

  static void PerVertexBorderFlag( MeshType &m, Color4b BorderColor=Color4b::Blue, Color4b InternalColor=Color4b::White, Color4b MixColor=Color4b::Cyan)
  {
    RequirePerVertexColor(m);

    Color4b BaseColor = Color4b::Green;

    PerVertexConstant(m,BaseColor);
    for(FaceIterator fi=m.face.begin();fi!=m.face.end();++fi) if(!(*fi).IsD())
      for(int j=0;j<3;++j)
      {
        if((*fi).IsB(j)){
          if( (*fi).V(j)->C() == BaseColor)     (*fi).V(j)->C() = BorderColor;
          if( (*fi).V(j)->C() == InternalColor) (*fi).V(j)->C() = MixColor;
          if( (*fi).V1(j)->C() == BaseColor)     (*fi).V1(j)->C() = BorderColor;
          if( (*fi).V1(j)->C() == InternalColor) (*fi).V1(j)->C() = MixColor;
        } else
        {
          if( (*fi).V(j)->C() == BaseColor)     (*fi).V(j)->C() = InternalColor;
          if( (*fi).V(j)->C() == BorderColor) (*fi).V(j)->C() = MixColor;
          if( (*fi).V1(j)->C() == BaseColor)     (*fi).V1(j)->C() = InternalColor;
          if( (*fi).V1(j)->C() == BorderColor) (*fi).V1(j)->C() = MixColor;
        }
      }

  }

  static void PerFaceRandomConnectedComponent( MeshType &m)
  {
    RequirePerFaceColor(m);
    RequireFFAdjacency(m);

    std::vector< std::pair<int, typename MeshType::FacePointer> > CCV;
    int ScatterSize= std::min (100,tri::Clean<MeshType>::ConnectedComponents(m, CCV)); // number of random color to be used. Never use too many.

    ConnectedComponentIterator<MeshType> ci;
    for(unsigned int i=0;i<CCV.size();++i)
    {
      Color4b BaseColor = Color4b::Scatter(ScatterSize, i%ScatterSize,.4f,.7f);
      std::vector<typename MeshType::FacePointer> FPV;
      for(ci.start(m,CCV[i].second);!ci.completed();++ci)
        (*ci)->C()=BaseColor;
    }
  }

  static void PerFaceRandom(MeshType &m)
  {
    RequirePerFaceColor(m);
    FaceIterator fi;
    Color4b BaseColor = Color4b::Black;
    PerFaceConstant(m,BaseColor);
    int id_num=0;
    for(fi=m.face.begin();fi!=m.face.end();++fi)
      if(!(*fi).IsD())
      {
        id_num++;
        if((*fi).C() == BaseColor) (*fi).C() = Color4b::Scatter(50, id_num%50,.4f,.7f);
        for(int j=0;j<3;++j)
          if((*fi).IsF(j))
          {
            assert(!IsBorder((*fi),j));
            (*fi).FFp(j)->C()= (*fi).C();
          }
      }
  }

static void PerVertexPerlinNoise(MeshType& m, CoordType period, CoordType offset = CoordType(0, 0, 0), bool onSelected = false)
{
        RequirePerVertexColor(m);

        CoordType p[3];
        
        for(VertexIterator vi = m.vert.begin(); vi!=m.vert.end(); ++vi)
                if(!(*vi).IsD())
                        if ((!onSelected) || ((*vi).IsS()))
                        {
                                // perlin noise is defined in 022
                                p[0] = (vi->P()/period[0])+offset;
                                p[1] = (vi->P()/period[1])+offset;
                                p[2] = (vi->P()/period[2])+offset;
                                (*vi).C() = Color4b(    int(127+128.0*math::Perlin::Noise(p[0][0],p[0][1],p[0][2])),
                                                                                int(127+128.0*math::Perlin::Noise(p[1][0],p[1][1],p[1][2])),
                                                                                int(127+128.0*math::Perlin::Noise(p[2][0],p[2][1],p[2][2])),
                                                                                255 );
                        }

}

static void PerVertexAddNoise(MeshType& m, int noiseBits, bool onSelected=false)
{
        RequirePerVertexColor(m);

        if(noiseBits>8) noiseBits = 8;
        if(noiseBits<1) return;

        math::SubtractiveRingRNG randomGen = math::SubtractiveRingRNG(time(NULL));
        for(VertexIterator vi = m.vert.begin(); vi!=m.vert.end(); ++vi)
                if(!(*vi).IsD())
                        if ((!onSelected) || ((*vi).IsS()))
                        {
                                (*vi).C()[0] = math::Clamp<int>((*vi).C()[0] + randomGen.generate(int(2*pow(2.0f,noiseBits))) - int(pow(2.0f,noiseBits)),0,255);
                                (*vi).C()[1] = math::Clamp<int>((*vi).C()[1] + randomGen.generate(int(2*pow(2.0f,noiseBits))) - int(pow(2.0f,noiseBits)),0,255);
                                (*vi).C()[2] = math::Clamp<int>((*vi).C()[2] + randomGen.generate(int(2*pow(2.0f,noiseBits))) - int(pow(2.0f,noiseBits)),0,255);
                        }
        
}


static int PerVertexThresholding(MeshType &m, float threshold, Color4b c1 = Color4<unsigned char>::Black, Color4b c2 = Color4<unsigned char>::White, const bool ProcessSelected=false)
{
  RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        float value = ComputeLightness((*vi).C());

        if(value<=threshold) (*vi).C() = c1;
        else (*vi).C() = c2;
        ++counter;
      }
    }
  }
  return counter;
}

// Computes the lightness value for a specified color. lightness = 0.5*(Max(R,G,B)+Min(R,G,B))
static float ComputeLightness(Color4b c)
{
  float min_rgb = (float)math::Min(c[0],c[1],c[2]);
  float max_rgb = (float)math::Max(c[0],c[1],c[2]);
  return (max_rgb + min_rgb)/2;
}

static int PerVertexBrightness(MeshType &m, float amount, const bool ProcessSelected=false)
{
  RequirePerVertexColor(m);

  int counter=0;
    VertexIterator vi;
    for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
    {
        if(!(*vi).IsD()) //if it has not been deleted...
        {
            if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = Color4b(
                            math::Clamp(int((*vi).C()[0]+amount),0,255),
                            math::Clamp(int((*vi).C()[1]+amount),0,255),
                            math::Clamp(int((*vi).C()[2]+amount),0,255),
                            255);
        ++counter;
      }
    }
  }
    return counter;
}

static int PerVertexContrast(MeshType &m, float factor, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorMul((*vi).C(),factor);
        ++counter;
      }
    }
  }
  return counter;
}

//Performs contrast operations on color, i.e expands or compress the histogram around
//the midpoint value.  NewValue = (OldValue - 128) ◊ factor + 128
static Color4b ColorMul(Color4b c, float factor)
{
  return Color4b( ValueMul(c[0], factor), ValueMul(c[1], factor), ValueMul(c[2], factor), 1);
}

static int ValueMul(int value, float factor)
{
  return math::Clamp<int>((int)((value - 128)*factor + 128), 0, 255);
}

static int PerVertexBrightnessContrast(MeshType &m, float brightness, float contrast, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorBrightnessContrast((*vi).C(),brightness,contrast);
        ++counter;
      }
    }
  }
  return counter;
}

static Color4b ColorBrightnessContrast(Color4b c, float brightness, float contrast)
{
  return Color4b( ValueBrightnessContrast(c[0], brightness, contrast),
                                    ValueBrightnessContrast(c[1], brightness, contrast),
                                    ValueBrightnessContrast(c[2], brightness, contrast), 1 );
}

static int ValueBrightnessContrast(unsigned char ivalue, float brightness, float contrast)
{
    float value = float(ivalue)/255.0f;
  if (brightness < 0.0)  value = value * ( 1.0 + brightness);
                    else value = value + ((1.0 - value) * brightness);
    value = (value - 0.5) * (tan ((contrast + 1) * M_PI/4) ) + 0.5;
    return math::Clamp<int>(255.0*value, 0, 255);
}

static int PerVertexInvert(MeshType &m, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  for(VertexIterator vi=m.vert.begin(); vi!=m.vert.end(); ++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        Color4b &c=(*vi).C();
        c=Color4b( 255-c[0],255-c[1],255-c[2], 1);
        ++counter;
      }
    }
  }
  return counter;
}

static int PerVertexGamma(MeshType &m, float gamma, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;

  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorPow((*vi).C(), 1/gamma);
        ++counter;
      }
    }
  }
  return counter;
}

//computes the standard gamma transformation on a given color, according to NewVal = OldVal^(1/gamma)
static Color4b ColorPow(Color4b c, float exponent)
{
  return vcg::Color4b(
                      math::Clamp((int)( ValuePow(float(c[0])/255, exponent)*255), 0, 255),
                      math::Clamp((int)( ValuePow(float(c[1])/255, exponent)*255), 0, 255),
                      math::Clamp((int)( ValuePow(float(c[2])/255, exponent)*255), 0, 255),
                      255);
}

static float ValuePow(float value, float exponent)
{
  return powf(value, exponent);
}

//useful bit masks for RGB channels, used for Levels filter.
enum rgbChMask {ALL_CHANNELS = 7, RED_CHANNEL = 4, GREEN_CHANNEL = 2, BLUE_CHANNEL = 1, NO_CHANNELS = 0 };

static int PerVertexLevels(MeshType &m, float gamma, float in_min, float in_max, float out_min, float out_max, unsigned char rgbMask, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorLevels((*vi).C(), gamma, in_min, in_max, out_min, out_max, rgbMask);
        ++counter;
      }
    }
  }
  return counter;
}

//Performs levels transformation on each channel set to 1 in the rgbMask.
static Color4b ColorLevels(Color4b c, float gamma, float in_min, float in_max, float out_min, float out_max, unsigned char rgbMask)
{
  unsigned char r = c[0], g = c[1], b = c[2];
  if(rgbMask & RED_CHANNEL) r = ValueLevels(c[0], gamma, in_min, in_max, out_min, out_max);
  if(rgbMask & GREEN_CHANNEL) g = ValueLevels(c[1], gamma, in_min, in_max, out_min, out_max);
  if(rgbMask & BLUE_CHANNEL) b = ValueLevels(c[2], gamma, in_min, in_max, out_min, out_max);
  return Color4b(r, g, b, 255);
}

//Transform on levels
static int ValueLevels(int value, float gamma, float in_min, float in_max, float out_min, float out_max)
{
  float fvalue = value/255.0f;
  // normalize
  fvalue = math::Clamp<float>(fvalue - in_min, 0.0f, 1.0f) / math::Clamp<float>(in_max - in_min, 1.0f/255.0f, 1.0f);
  // transform gamma
  fvalue = powf(fvalue,1/gamma);
  // rescale range
  fvalue = fvalue * (out_max - out_min) + out_min;
  //back in interval [0,255] and clamp
  return math::Clamp<int>((int)(fvalue * 255), 0, 255);
}

static int PerVertexColourisation(MeshType &m, Color4b c, float intensity, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi)
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorApplyDiff((*vi).C(), c, intensity);
        ++counter;
      }
    }
  }
  return counter;
}

// Perform colourisation operation.
// For each channel C:
// newC = origC + intensity * (newC - origC)
static Color4b ColorApplyDiff(Color4b old_color, Color4b new_color, float intensity)
{
  return Color4b( ValueApplyDiff(old_color[0], new_color[0], intensity),
                  ValueApplyDiff(old_color[1], new_color[1], intensity),
                  ValueApplyDiff(old_color[2], new_color[2], intensity), 255);
}

static int ValueApplyDiff(int old_value, int new_value, float intensity)
{
  return  math::Clamp<int>((int)(old_value + intensity * (new_value - old_value)), 0, 255);
}

//An useful ENUM to hold all desaturation methods.
enum DesaturationMethods {M_LIGHTNESS = 0, M_LUMINOSITY = 1, M_AVERAGE = 2};

static int PerVertexDesaturation(MeshType &m, int method, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  int counter=0;
  VertexIterator vi;
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C() = ColorDesaturate((*vi).C(), method);
        ++counter;
      }
    }
  }
  return counter;
}

//Desature the color. Ausiliary functions to calculate lightness/luminosity/average.
static Color4b ColorDesaturate(Color4b c, int method)
{
  switch(method){
    case M_LIGHTNESS:{
      int val = (int)ComputeLightness(c);
      return Color4b( val, val, val, 255);
    }
    case M_AVERAGE:{
      int val = (int)ComputeAvgLightness(c);
      return Color4b( val, val, val, 255);
    }
    case M_LUMINOSITY:{
      int val = (int)ComputeLuminosity(c);
      return Color4b( val, val, val, 255);
    }
    default: assert(0);
  }
}

//ausiliary function to compute average lightness. value = (R+G+B)/3
static float ComputeAvgLightness(Color4b c)
{
    return float(c[0]+c[1]+c[2])/3.0f;
}

//ausiliary function to compute luminosity. value = 0.21*R+0.71*G+0.7*B
static float ComputeLuminosity(Color4b c)
{
    return float(0.2126f*c[0]+0.7152f*c[1]+0.0722f*c[2]);
}

static int PerVertexEqualize(MeshType &m, unsigned int rgbMask, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  //declares , resets and set up 4 histograms, for Red, Green, Blue and Lightness
  Histogramf Hl, Hr, Hg, Hb;
  Hl.Clear(); Hr.Clear(); Hg.Clear(); Hb.Clear();
  Hl.SetRange(0, 255, 255); Hr.SetRange(0, 255, 255); Hg.SetRange(0, 255, 255); Hb.SetRange(0, 255, 255);

  int counter=0;
  VertexIterator vi;

  //Scan the mesh to build the histograms
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, put it in the histograms
      {
        float v = ComputeLightness((*vi).C())+0.5; //compute and round lightness value
        Hl.Add(v); Hr.Add((float)(*vi).C()[0]); Hg.Add((float)(*vi).C()[1]); Hb.Add((float)(*vi).C()[2]);
      }
    }
  }

  //for each histogram, compute the cumulative distribution function, and build a lookup table
    int cdf_l[256], cdf_r[256], cdf_g[256], cdf_b[256];
    cdf_l[0] = Hl.BinCount(0); cdf_r[0] = Hr.BinCount(0); cdf_g[0] = Hg.BinCount(0); cdf_b[0] = Hb.BinCount(0);
    for(int i=1; i<256; i++){
    cdf_l[i] = Hl.BinCount(float(i)) + cdf_l[i-1];
    cdf_r[i] = Hr.BinCount(float(i)) + cdf_r[i-1];
    cdf_g[i] = Hg.BinCount(float(i)) + cdf_g[i-1];
    cdf_b[i] = Hb.BinCount(float(i)) + cdf_b[i-1];
  }

  //this loop aaplies the transformation to colors
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C()=ColorEqualize((*vi).C(), cdf_l, cdf_r, cdf_g, cdf_b, rgbMask);
        ++counter;
      }
    }
  }
  return counter;
}

//Applies equalization to the components of the color according to rgbmask
static Color4b ColorEqualize(Color4b c, int cdf_l[256], int cdf_r[256], int cdf_g[256], int cdf_b[256], unsigned int rgbMask)
{
  unsigned char r = c[0], g = c[1], b = c[2];
  if(rgbMask == NO_CHANNELS) //in this case, equalization is done on lightness
  {
    int v = ValueEqualize(cdf_l[(int)(ComputeLightness(c)+0.5f)], cdf_l[0], cdf_l[255]);
    return Color4b(v, v, v, 255); //return the equalized gray color
  }
  if(rgbMask & RED_CHANNEL) r = ValueEqualize(cdf_r[c[0]], cdf_r[0], cdf_r[255]); //Equalizes red
  if(rgbMask & GREEN_CHANNEL) g = ValueEqualize(cdf_g[c[1]], cdf_g[0], cdf_g[255]); //Equalizes green
  if(rgbMask & BLUE_CHANNEL) b = ValueEqualize(cdf_b[c[2]], cdf_b[0], cdf_b[255]); //Equalizes blue
  return Color4b(r, g, b, 255); //return the equalized color
}

//Compute the equalized value
static int ValueEqualize(int cdfValue, int cdfMin, int cdfMax)
{
  return int(float((cdfValue - cdfMin)/float(cdfMax - cdfMin)) * 255.0f);
}

static int PerVertexWhiteBalance(MeshType &m, Color4b userColor, const bool ProcessSelected=false)
{
      RequirePerVertexColor(m);

  Color4b unbalancedWhite= userColor;
  int counter=0;
  VertexIterator vi;

  //in this loop the transformation is applied to the mesh
  for(vi=m.vert.begin();vi!=m.vert.end();++vi) //scan all the vertex...
  {
    if(!(*vi).IsD()) //if it has not been deleted...
    {
      if(!ProcessSelected || (*vi).IsS()) //if this vertex has been selected, do transormation
      {
        (*vi).C()=ColorWhiteBalance((*vi).C(),unbalancedWhite);
        ++counter;
      }
    }
  }
  return counter;
}

//Balnce the white of the color, applying a correction factor based on the unbalancedWhite color.
static Color4b ColorWhiteBalance(Color4b c, Color4b unbalancedWhite)
{
  //sanity check to avoid division by zero...
  if(unbalancedWhite[0]==0) unbalancedWhite[0]=1;
  if(unbalancedWhite[1]==0) unbalancedWhite[1]=1;
  if(unbalancedWhite[2]==0) unbalancedWhite[2]=1;

  return Color4b(
                 math::Clamp<int>((int)(c[0]*(255.0f/unbalancedWhite[0])), 0, 255),
                 math::Clamp<int>((int)(c[1]*(255.0f/unbalancedWhite[1])), 0, 255),
                 math::Clamp<int>((int)(c[2]*(255.0f/unbalancedWhite[2])), 0, 255),
                 255);
}

};

}// end namespace
}// end namespace
#endif