// -------------------------------------------------------------------------
// @author Leonardo Florez-Valencia (florez-l@javeriana.edu.co)
// -------------------------------------------------------------------------

#ifndef __CPPLUGINS__EXTENSIONS__ALGORITHMS__RGBTOYPBPRFUNCTION__H__
#define __CPPLUGINS__EXTENSIONS__ALGORITHMS__RGBTOYPBPRFUNCTION__H__

#include <cmath>
#include <limits>
#include <vnl/vnl_math.h>
#include <vnl/vnl_matrix.h>

#include <itkRGBPixel.h>
#include <itkMatrix.h>
#include <itkVector.h>

namespace cpPlugins
{
  namespace Extensions
  {
    namespace Algorithms
    {
      /**
       */
      template< class O >
      struct RGBToYPbPrFunction
      {
        typedef RGBToYPbPrFunction  Self;
        typedef itk::Vector< O, 3 > TOutPixel;

        template< class Tr, class Tg, class Tb >
        TOutPixel operator()( const Tr& r, const Tg& g, const Tb& b ) const
          {
            static const O M[] =
              {
                O(  0.299 ), O(  0.587 ), O(  0.114 ),
                O( -0.169 ), O( -0.331 ), O(  0.500 ),
                O(  0.500 ), O( -0.419 ), O( -0.081 )
              };
            static const vnl_matrix< O > vM( M, 3, 3 );
            static const itk::Matrix< O, 3, 3 > iM( vM );

            TOutPixel rgb;
            rgb[ 0 ] = O( r );
            rgb[ 1 ] = O( g );
            rgb[ 2 ] = O( b );
            return( iM * rgb );
          }

        template< class C >
        TOutPixel operator()( const itk::RGBPixel< C >& rgb ) const
          {
            return(
              this->operator()(
                rgb.GetRed( ), rgb.GetGreen( ), rgb.GetBlue( )
                )
              );
          }
      };

    } // ecapseman

  } // ecapseman

} // ecapseman

#endif // __CPPLUGINS__EXTENSIONS__ALGORITHMS__RGBTOYPBPRFUNCTION__H__

// eof - $RCSfile$