message: Threshold Ora LUT for negative values
diff: @@ -71,6 +71,13 @@ OraLookupTableImageFilter<TOutputImage>
  it.GoToBegin();
  if(m_ComputeLineIntegral)
  {
  + int negidx = itk::Math::Floor<int, double>(std::floor(-intercept/slope));
  + double negval = -1. * vcl_log(slope * (negidx+1) + intercept);
  + while( !it.IsAtEnd() && (int)it.GetIndex()[0] <= negidx )
  + {
  + it.Set(negval);
  + ++it;
  + }
  while( !it.IsAtEnd() )
  {
  it.Set( -1. * vcl_log(slope * it.GetIndex()[0] + intercept) );
  