void Correlation( IplImage *LeftImage, IplImage *RightImage, int WindowSize, int x, int y ) {
  dmPixel LeftPixel;
  dmPixel RightPixel;
  int j, i, dx, dj, di;
  int WindowHalf = ( WindowSize - 1 ) / 2;
  float numerator, denominator[2], result;
  int LAverageWindowBrightness, RAverageWindowBrightness;

  for( j = y - WindowHalf; j <= y + WindowHalf; j++ ) {
    for( i = x - WindowHalf; i <= x + WindowHalf; i++ ) {
      LAverageWindowBrightness += DM_BRIGHTNESS( GetPixel( LeftImage->imageData, LeftImage->widthStep, i, j ) );
    }
  }
  LAverageWindowBrightness /= WindowSize * WindowSize;
  LeftPixel = GetPixel( LeftImage->imageData, LeftImage->widthStep, x, y );

  for( j = y - WindowHalf; j <= y + WindowHalf; j++ ) {
    for( i = x - WindowHalf; i <= x + WindowHalf; i++ ) {

      RightPixel = GetPixel( RightImage->imageData, LeftImage->widthStep, x + i, y + j );
      for( dj = j - WindowHalf; dj <= j + WindowHalf; dj++ ) {
        for( di = i - WindowHalf; di <= i + WindowHalf; di++ ) {
          RAverageWindowBrightness += DM_BRIGHTNESS( GetPixel( RightImage->imageData, RightImage->widthStep, i, j ) );
        }
      }
      RAverageWindowBrightness /= WindowSize * WindowSize;

      numerator += pow( ( DM_BRIGHTNESS( LeftPixel ) - LAverageWindowBrightness ) - ( DM_BRIGHTNESS( RightPixel ) - RAverageWindowBrightness ), 2.0f );
      denominator[0] += pow( ( DM_BRIGHTNESS( LeftPixel ) - LAverageWindowBrightness ), 2.0f );
      denominator[1] += pow( ( DM_BRIGHTNESS( RightPixel ) - RAverageWindowBrightness ), 2.0f );
    }
  }
  result = numerator / ( denominator[0] * denominator[1] );
}