/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkImageRGBToHSI.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
#include "vtkImageRGBToHSI.h"

#include "vtkImageData.h"
#include "vtkImageProgressIterator.h"
#include "vtkObjectFactory.h"

#include <math.h>

vtkStandardNewMacro(vtkImageRGBToHSI);

//----------------------------------------------------------------------------
vtkImageRGBToHSI::vtkImageRGBToHSI()
{
  this->Maximum = 255.0;
  this->SetNumberOfInputPorts(1);
  this->SetNumberOfOutputPorts(1);
}

//----------------------------------------------------------------------------
// This templated function executes the filter for any type of data.
template <class T>
void vtkImageRGBToHSIExecute(vtkImageRGBToHSI *self,
                             vtkImageData *inData,
                             vtkImageData *outData,
                             int outExt[6], int id, T *)
{
  vtkImageIterator<T> inIt(inData, outExt);
  vtkImageProgressIterator<T> outIt(outData, outExt, self, id);
  int idxC, maxC;
  double R, G, B, H, S, I;
  double max = self->GetMaximum();
  double temp;
  
  // find the region to loop over
  maxC = inData->GetNumberOfScalarComponents()-1;
  
  // Loop through ouput pixels
  while (!outIt.IsAtEnd())
    {
    T* inSI = inIt.BeginSpan();
    T* outSI = outIt.BeginSpan();
    T* outSIEnd = outIt.EndSpan();
    while (outSI != outSIEnd)
      {
      // Pixel operation
      R = static_cast<double>(*inSI); inSI++;
      G = static_cast<double>(*inSI); inSI++;
      B = static_cast<double>(*inSI); inSI++;
      // Saturation
      temp = R;
      if (G < temp)
        {
        temp = G;
        }
      if (B < temp)
        {
        temp = B;
        }
      double sumRGB = R+G+B;
      if(sumRGB == 0.0)
        {
        S = 0.0;
        }
      else
        {
        S = max * (1.0 - (3.0 * temp / sumRGB));
        }
      
      temp = static_cast<double>(R + G + B);
      // Intensity is easy
      I = temp / 3.0;
      
      // Hue
      temp = sqrt((R-G)*(R-G) + (R-B)*(G-B));
      if(temp != 0.0)
        {
        temp = acos((0.5 * ((R-G) + (R-B))) / temp);
        }
      if (G >= B)
        {
        H = max * (temp / 6.2831853);
        }
      else
        {
        H = max * (1.0 - (temp / 6.2831853));
        }
      
      // assign output.
      *outSI = static_cast<T>(H); outSI++;
      *outSI = static_cast<T>(S); outSI++;
      *outSI = static_cast<T>(I); outSI++;
      
      for (idxC = 3; idxC <= maxC; idxC++)
        {
        *outSI++ = *inSI++;
        }
      }
    inIt.NextSpan();
    outIt.NextSpan();
    }
}

//----------------------------------------------------------------------------
void vtkImageRGBToHSI::ThreadedExecute (vtkImageData *inData, 
                                         vtkImageData *outData,
                                         int outExt[6], int id)
{
  vtkDebugMacro(<< "Execute: inData = " << inData 
  << ", outData = " << outData);
  
  // this filter expects that input is the same type as output.
  if (inData->GetScalarType() != outData->GetScalarType())
    {
    vtkErrorMacro(<< "Execute: input ScalarType, " << inData->GetScalarType()
    << ", must match out ScalarType " << outData->GetScalarType());
    return;
    }
  
  // need three components for input and output
  if (inData->GetNumberOfScalarComponents() < 3)
    {
    vtkErrorMacro("Input has too few components");
    return;
    }
  if (outData->GetNumberOfScalarComponents() < 3)
    {
    vtkErrorMacro("Output has too few components");
    return;
    }

  switch (inData->GetScalarType())
    {
    vtkTemplateMacro(
      vtkImageRGBToHSIExecute( this, inData, 
                               outData, outExt, id, 
                               static_cast<VTK_TT *>(0)));
    default:
      vtkErrorMacro(<< "Execute: Unknown ScalarType");
      return;
    }
}

void vtkImageRGBToHSI::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);

  os << indent << "Maximum: " << this->Maximum << "\n";
}