itkNrrdImageIO.cxx

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

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkNrrdImageIO.cxx,v $
  Language:  C++
  Date:      $Date: 2007-05-16 19:44:55 $
  Version:   $Revision: 1.38 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/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 notices for more information.

=========================================================================*/
#ifdef _MSC_VER
#pragma warning ( disable : 4786 )
#endif

#include <string>
#include "itkNrrdImageIO.h"
#include "itkMacro.h"
#include "itkMetaDataObject.h"
#include "itkIOCommon.h"

#if defined(__BORLANDC__) 
# include <math.h> 
# include <float.h> // for _control87() 
#endif // defined(__BORLANDC__) 

namespace itk {

#define KEY_PREFIX "NRRD_"
 
bool NrrdImageIO::SupportsDimension(unsigned long dim)
{
  if (1 == this->GetNumberOfComponents())
    {
    return dim <= NRRD_DIM_MAX;
    }
  else
    {
    return dim <= NRRD_DIM_MAX - 1;
    }
}

void NrrdImageIO::PrintSelf(std::ostream& os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
}
 
ImageIOBase::IOComponentType
NrrdImageIO::
NrrdToITKComponentType( const int nrrdComponentType ) const
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 
  switch( nrrdComponentType )
    {
    case nrrdTypeUnknown:
    case nrrdTypeBlock:
      return UNKNOWNCOMPONENTTYPE;
      break;
    case nrrdTypeChar:
      return CHAR;
      break;
    case nrrdTypeUChar:
      return UCHAR;
      break;
    case nrrdTypeShort:
      return SHORT;
      break;
    case nrrdTypeUShort:
      return USHORT;
      break;
    // "long" is a silly type because it basically guaranteed not to be
    // cross-platform across 32-vs-64 bit machines, but we'll use it 
    // where possible.
    case nrrdTypeLLong:
      return airMy32Bit ? UNKNOWNCOMPONENTTYPE : LONG;
      break;
    case nrrdTypeULLong:
      return airMy32Bit ? UNKNOWNCOMPONENTTYPE : ULONG;
      break;
    case nrrdTypeInt:
      return INT;
      break;
    case nrrdTypeUInt:
      return UINT;
      break;
    case nrrdTypeFloat:
      return FLOAT;
      break;
    case nrrdTypeDouble:
      return DOUBLE;
      break;
    default:
      return UNKNOWNCOMPONENTTYPE;
      break;
    }

  // Strictly to avoid compiler warning regarding "control may reach end of
  // non-void function":
  //
  return UNKNOWNCOMPONENTTYPE;
}

int
NrrdImageIO::
ITKToNrrdComponentType( const ImageIOBase::IOComponentType itkComponentType ) const
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 
  switch( itkComponentType )
    {
    case UNKNOWNCOMPONENTTYPE:
      return nrrdTypeUnknown;
      break;
    case CHAR:
      return nrrdTypeChar;
      break;
    case UCHAR:
      return nrrdTypeUChar;
      break;
    case SHORT:
      return nrrdTypeShort;
      break;
    case USHORT:
      return nrrdTypeUShort;
      break;
    // "long" is a silly type because it basically guaranteed not to be
    // cross-platform across 32-vs-64 bit machines, but we can figure out
    // a cross-platform way of storing the information.
    case LONG:
      return airMy32Bit ? nrrdTypeInt : nrrdTypeLLong;
      break;
    case ULONG:
      return airMy32Bit ? nrrdTypeUInt : nrrdTypeULLong;
      break;
    case INT:
      return nrrdTypeInt;
      break;
    case UINT:
      return nrrdTypeUInt;
      break;
    case FLOAT:
      return nrrdTypeFloat;
      break;
    case DOUBLE:
      return nrrdTypeDouble;
      break;
    default:
      return nrrdTypeUnknown;
      break;
    }

  // Strictly to avoid compiler warning regarding "control may reach end of
  // non-void function":
  //
  return nrrdTypeUnknown;
}

bool NrrdImageIO::CanReadFile( const char* filename ) 
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 
  // Check the extension first to avoid opening files that do not
  // look like nrrds.  The file must have an appropriate extension to be
  // recognized.
  std::string fname = filename;
  if(  fname == "" )
    {
    itkDebugMacro(<<"No filename specified.");
    return false;
    }

  bool extensionFound = false;
  std::string::size_type nrrdPos = fname.rfind(".nrrd");
  if ((nrrdPos != std::string::npos)
      && (nrrdPos == fname.length() - 5))
    {
    extensionFound = true;
    }

  std::string::size_type nhdrPos = fname.rfind(".nhdr");
  if ((nhdrPos != std::string::npos)
      && (nhdrPos == fname.length() - 5))
    {
    extensionFound = true;
    }

  if( !extensionFound )
    {
    itkDebugMacro(<<"The filename extension is not recognized");
    return false;
    }

  // We have the correct extension, so now check for the Nrrd magic "NRRD",
  // while ignoring the format version (the next four characters)
  std::ifstream inputStream;

  inputStream.open( filename, std::ios::in | std::ios::binary );

  if( inputStream.fail() )
    {
    return false;
    }

  char magic[5] = {'\0','\0','\0','\0','\0'};
  inputStream.read(magic,4*sizeof(char));

  if( inputStream.eof() )
    {
    inputStream.close();
    return false;
    }

  if( strcmp(magic,"NRRD") == 0 ) 
    {
    inputStream.close();
    return true;
    }

  inputStream.close();
  return false;
}

void NrrdImageIO::ReadImageInformation()
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 
  // This method determines the following and sets the appropriate value in
  // the parent IO class:
  //
  // binary/ascii file type 
  // endianness
  // pixel type
  // pixel component type
  // number of pixel components
  // number of image dimensions
  // image spacing
  // image origin
  // meta data dictionary information
  
  Nrrd *nrrd = nrrdNew();
  NrrdIoState *nio = nrrdIoStateNew();
  
  // this is the mechanism by which we tell nrrdLoad to read
  // just the header, and none of the data
  nrrdIoStateSet(nio, nrrdIoStateSkipData, 1);
  if (nrrdLoad(nrrd, this->GetFileName(), nio) != 0)
    {
    char *err = biffGetDone(NRRD);  // would be nice to free(err)
    itkExceptionMacro("ReadImageInformation: Error reading " 
                      << this->GetFileName() << ":\n" << err);
    }

  if (nrrdTypeBlock == nrrd->type)
    {
    itkExceptionMacro("ReadImageInformation: Cannot currently "
                      "handle nrrdTypeBlock");
    }
  if ( nio->endian == airEndianLittle )
    {
    this->SetByteOrderToLittleEndian();
    }
  else if (nio->endian == airEndianBig )
    {
    this->SetByteOrderToBigEndian();
    }
  else
    {
    this->SetByteOrder( ImageIOBase::OrderNotApplicable );
    }

  if ( nio->encoding == nrrdEncodingAscii )
    {
    this->SetFileTypeToASCII();
    }
  else
    {
    this->SetFileTypeToBinary();
    }
  // set type of pixel components; this is orthogonal to pixel type

  ImageIOBase::IOComponentType
    cmpType = this->NrrdToITKComponentType(nrrd->type);
  if (UNKNOWNCOMPONENTTYPE == cmpType)
    {
    itkExceptionMacro("Nrrd type " << airEnumStr(nrrdType, nrrd->type)
                      << " could not be mapped to an ITK component type");
    }
  this->SetComponentType( cmpType );

  // Set the number of image dimensions and bail if needed
  unsigned int domainAxisNum, domainAxisIdx[NRRD_DIM_MAX],
    rangeAxisNum, rangeAxisIdx[NRRD_DIM_MAX];
  domainAxisNum = nrrdDomainAxesGet(nrrd, domainAxisIdx);
  rangeAxisNum = nrrdRangeAxesGet(nrrd, rangeAxisIdx);
  if (nrrd->spaceDim && nrrd->spaceDim != domainAxisNum)
    {
    itkExceptionMacro("ReadImageInformation: nrrd's # independent axes ("
                      << domainAxisNum << ") doesn't match dimension of space"
                      " in which orientation is defined ("
                      << nrrd->spaceDim << "); not currently handled");
    }
  // else nrrd->spaceDim == domainAxisNum when nrrd has orientation
  
  if (0 == rangeAxisNum)
    {
    // we don't have any non-scalar data
    this->SetNumberOfDimensions(nrrd->dim);
    this->SetPixelType( ImageIOBase::SCALAR );
    this->SetNumberOfComponents(1);
    }
  else if (1 == rangeAxisNum)
    {
    this->SetNumberOfDimensions(nrrd->dim - 1);
    unsigned int kind = nrrd->axis[rangeAxisIdx[0]].kind;
    unsigned int size = nrrd->axis[rangeAxisIdx[0]].size;
    // NOTE: it is the NRRD readers responsibility to make sure that
    // the size (# of components) associated with a specific kind is
    // matches the actual size of the axis.
    switch(kind)
      {
      case nrrdKindDomain:
      case nrrdKindSpace:
      case nrrdKindTime:
        itkExceptionMacro("ReadImageInformation: range axis kind ("
                          << airEnumStr(nrrdKind, kind) << ") seems more "
                          "like a domain axis than a range axis");
        break;
      case nrrdKindStub:
      case nrrdKindScalar:
        this->SetPixelType( ImageIOBase::SCALAR );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKind3Color:
      case nrrdKindRGBColor:
        this->SetPixelType( ImageIOBase::RGB );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKind4Color:
      case nrrdKindRGBAColor:
        this->SetPixelType( ImageIOBase::RGBA );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKindVector:
      case nrrdKind2Vector:
      case nrrdKind3Vector:
      case nrrdKind4Vector:
      case nrrdKindList:
        this->SetPixelType( ImageIOBase::VECTOR );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKindPoint:
        this->SetPixelType( ImageIOBase::POINT );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKindCovariantVector:
      case nrrdKind3Gradient:
      case nrrdKindNormal:
      case nrrdKind3Normal:
        this->SetPixelType( ImageIOBase::COVARIANTVECTOR );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKind3DSymMatrix:
        // ImageIOBase::DIFFUSIONTENSOR3D is a subclass
        this->SetPixelType( ImageIOBase::SYMMETRICSECONDRANKTENSOR );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKind3DMaskedSymMatrix:
        this->SetPixelType( ImageIOBase::SYMMETRICSECONDRANKTENSOR );
        // NOTE: we will crop out the mask in Read() below; this is the
        // one case where NumberOfComponents != size
        this->SetNumberOfComponents(size-1);
        break;
      case nrrdKindComplex:
        this->SetPixelType( ImageIOBase::COMPLEX );
        this->SetNumberOfComponents(size);
        break;
      case nrrdKindHSVColor:
      case nrrdKindXYZColor:
      case nrrdKindQuaternion:
      case nrrdKind2DSymMatrix:
      case nrrdKind2DMaskedSymMatrix:
      case nrrdKind2DMatrix:
      case nrrdKind2DMaskedMatrix:
      case nrrdKind3DMatrix:
        // for all other Nrrd kinds, we punt and call it a vector
        this->SetPixelType( ImageIOBase::VECTOR );
        this->SetNumberOfComponents(size);
        break;
      default:
        itkExceptionMacro("ReadImageInformation: nrrdKind " << kind 
                          << " not known!");
        break;
      }
    }
  else 
    {
    itkExceptionMacro("ReadImageInformation: nrrd has "
                      << rangeAxisNum 
                      << " dependent axis (not 1); not currently handled");
    }
  
  double spacing;
  double spaceDir[NRRD_SPACE_DIM_MAX];
  std::vector<double> spaceDirStd(domainAxisNum);
  int spacingStatus;
  
  int iFlipFactors[3];  // used to flip the measurement frame later on
  for (unsigned int iI=0; iI<3; iI++ )
    {
    iFlipFactors[iI] = 1;
    }

  for (unsigned int axii=0; axii < domainAxisNum; axii++)
    {
    unsigned int naxi = domainAxisIdx[axii];
    this->SetDimensions(axii, nrrd->axis[naxi].size);
    spacingStatus = nrrdSpacingCalculate(nrrd, naxi, &spacing, spaceDir);

    switch(spacingStatus) 
      {
      case nrrdSpacingStatusNone:
        // Let ITK's defaults stay
        // this->SetSpacing(axii, 1.0);
        break;
      case nrrdSpacingStatusScalarNoSpace:
        this->SetSpacing(axii, spacing);
        break;
      case nrrdSpacingStatusDirection:
        if (AIR_EXISTS(spacing))
          {
          // only set info if we have something to set
          switch (nrrd->space)
            {
            // on read, convert non-LPS coords into LPS coords, when we can
            case nrrdSpaceRightAnteriorSuperior:
              spaceDir[0] *= -1;   // R -> L
              spaceDir[1] *= -1;   // A -> P
              iFlipFactors[0] = -1;
              iFlipFactors[1] = -1;
              break;
            case nrrdSpaceLeftAnteriorSuperior:
              spaceDir[0] *= -1;   // R -> L
              iFlipFactors[0] = -1;
              break;
            case nrrdSpaceLeftPosteriorSuperior:
              // no change needed
              break;
            default:
              // we're not coming from a space for which the conversion
              // to LPS is well-defined
              break;
            }
          this->SetSpacing(axii, spacing);

          for (unsigned int saxi=0; saxi < nrrd->spaceDim; saxi++)
            {
            spaceDirStd[saxi] = spaceDir[saxi];
            }
          this->SetDirection(axii, spaceDirStd);
          }
        break;
      default:
      case nrrdSpacingStatusUnknown:
        itkExceptionMacro("ReadImageInformation: Error interpreting "
                          "nrrd spacing (nrrdSpacingStatusUnknown)");
        break;
      case nrrdSpacingStatusScalarWithSpace:
        itkExceptionMacro("ReadImageInformation: Error interpreting "
                          "nrrd spacing (nrrdSpacingStatusScalarWithSpace)");
        break;
      }
    }
  
  // Figure out origin
  if (nrrd->spaceDim)
    {
    if (AIR_EXISTS(nrrd->spaceOrigin[0]))
      {
      // only set info if we have something to set
      double spaceOrigin[NRRD_SPACE_DIM_MAX];
      for (unsigned int saxi=0; saxi < nrrd->spaceDim; saxi++)
        {
        spaceOrigin[saxi] = nrrd->spaceOrigin[saxi];
        }
      switch (nrrd->space)
        {
        // convert non-LPS coords into LPS coords, when we can
        case nrrdSpaceRightAnteriorSuperior:
          spaceOrigin[0] *= -1;   // R -> L
          spaceOrigin[1] *= -1;   // A -> P
          break;
        case nrrdSpaceLeftAnteriorSuperior:
          spaceOrigin[0] *= -1;   // R -> L
          break;
        case nrrdSpaceLeftPosteriorSuperior:
          // no change needed
          break;
        default:
          // we're not coming from a space for which the conversion
          // to LPS is well-defined
          break;
        }
      for (unsigned int saxi=0; saxi < nrrd->spaceDim; saxi++)
        {
        this->SetOrigin(saxi, spaceOrigin[saxi]);
        }
      }
    }
  else 
    {
    double spaceOrigin[NRRD_DIM_MAX];
    int originStatus = nrrdOriginCalculate(nrrd, domainAxisIdx, domainAxisNum,
                                           nrrdCenterCell, spaceOrigin);
    for (unsigned int saxi=0; saxi < domainAxisNum; saxi++) 
      {
      switch (originStatus)
        {
        case nrrdOriginStatusNoMin:
        case nrrdOriginStatusNoMaxOrSpacing:
          // only set info if we have something to set
          // this->SetOrigin(saxi, 0.0);
          break;
        case nrrdOriginStatusOkay:
          this->SetOrigin(saxi, spaceOrigin[saxi]);
          break;
        default:
        case nrrdOriginStatusUnknown:
        case nrrdOriginStatusDirection:
          itkExceptionMacro("ReadImageInformation: Error interpreting "
                            "nrrd origin status");
          break;
        }
      }
    }

  // Store key/value pairs in MetaDataDictionary
  char key[AIR_STRLEN_SMALL];
  const char *val;
  char *keyPtr = NULL;
  char *valPtr = NULL;
  MetaDataDictionary &thisDic=this->GetMetaDataDictionary();
  std::string classname(this->GetNameOfClass());
  EncapsulateMetaData<std::string>(thisDic, ITK_InputFilterName, classname);
  for (unsigned int kvpi=0; kvpi < nrrdKeyValueSize(nrrd); kvpi++)
    {
    nrrdKeyValueIndex(nrrd, &keyPtr, &valPtr, kvpi);
    EncapsulateMetaData<std::string>(thisDic, std::string(keyPtr), 
                                     std::string(valPtr));
    keyPtr = (char *)airFree(keyPtr);
    valPtr = (char *)airFree(valPtr);
    }
  
  // save in MetaDataDictionary those important nrrd fields that
  // (currently) have no ITK equivalent. NOTE that for the per-axis
  // information, we use the same axis index (axii) as in ITK, NOT
  // the original axis index in nrrd (axi).  This is because in the
  // Read() method, non-scalar data is permuted to the fastest axis,
  // on the on the Write() side, its always written to the fastest axis,
  // so we might was well go with consistent and idiomatic indexing.
  NrrdAxisInfo *naxis;
  for (unsigned int axii=0; axii < domainAxisNum; axii++)
    {
    unsigned int axi = domainAxisIdx[axii];
    naxis = nrrd->axis + axi;
    if (AIR_EXISTS(naxis->thickness))
      {
      sprintf(key, "%s%s[%d]", KEY_PREFIX,
              airEnumStr(nrrdField, nrrdField_thicknesses), axii);
      EncapsulateMetaData<double>(thisDic, std::string(key),
                                  naxis->thickness);
      }
    if (naxis->center)
      {
      sprintf(key, "%s%s[%d]", KEY_PREFIX, 
              airEnumStr(nrrdField, nrrdField_centers), axii);
      val = airEnumStr(nrrdCenter, naxis->center);
      EncapsulateMetaData<std::string>(thisDic, std::string(key),
                                       std::string(val));
      }
    if (naxis->kind)
      {
      sprintf(key, "%s%s[%d]", KEY_PREFIX, 
              airEnumStr(nrrdField, nrrdField_kinds), axii);
      val = airEnumStr(nrrdKind, naxis->kind);
      EncapsulateMetaData<std::string>(thisDic, std::string(key),
                                       std::string(val));
      }
    if (airStrlen(naxis->label))
      {
      sprintf(key, "%s%s[%d]", KEY_PREFIX, 
              airEnumStr(nrrdField, nrrdField_labels), axii);
      EncapsulateMetaData<std::string>(thisDic, std::string(key),
                                       std::string(naxis->label));
      }
    }
  if (airStrlen(nrrd->content))
    {
    sprintf(key, "%s%s", KEY_PREFIX, 
            airEnumStr(nrrdField, nrrdField_content));
    EncapsulateMetaData<std::string>(thisDic, std::string(key), 
                                     std::string(nrrd->content));
    }
  if (AIR_EXISTS(nrrd->oldMin))
    {
    sprintf(key, "%s%s", KEY_PREFIX,
            airEnumStr(nrrdField, nrrdField_old_min));
    EncapsulateMetaData<double>(thisDic, std::string(key), nrrd->oldMin);
    }
  if (AIR_EXISTS(nrrd->oldMax))
    {
    sprintf(key, "%s%s", KEY_PREFIX,
            airEnumStr(nrrdField, nrrdField_old_max));
    EncapsulateMetaData<double>(thisDic, std::string(key), nrrd->oldMax);
    }
  if (nrrd->space)
    {
    sprintf(key, "%s%s", KEY_PREFIX,
            airEnumStr(nrrdField, nrrdField_space));
    val = airEnumStr(nrrdSpace, nrrd->space);

    // keep everything consistent: so enter it as LPS in the meta data
    // dictionary in case it could get converted, otherwise leave it
    // as is

    switch (nrrd->space) 
      {
      case nrrdSpaceRightAnteriorSuperior:
      case nrrdSpaceLeftAnteriorSuperior:
      case nrrdSpaceLeftPosteriorSuperior:
        // in all these cases we could convert
        EncapsulateMetaData<std::string>(thisDic, std::string(key),
                                         std::string( airEnumStr(nrrdSpace, nrrdSpaceLeftPosteriorSuperior )));
        break;
      default:
        // we're not coming from a space for which the conversion
        // to LPS is well-defined
        EncapsulateMetaData<std::string>(thisDic, std::string(key),
                                         std::string(val));
        break;
      }
    }

  if (AIR_EXISTS(nrrd->measurementFrame[0][0]))
    {
    sprintf(key, "%s%s", KEY_PREFIX,
            airEnumStr(nrrdField, nrrdField_measurement_frame));
    std::vector<std::vector<double> > msrFrame(domainAxisNum);

    // flip the measurement frame here if we have to 
    // so that everything is consistent with the ITK LPS space directions
    // but only do this if we have a three dimensional space or smaller

    for (unsigned int saxi=0; saxi < domainAxisNum; saxi++) 
      {
      msrFrame[saxi].resize(domainAxisNum);
      for (unsigned int saxj=0; saxj < domainAxisNum; saxj++)
        {
        if ( domainAxisNum<=3 ) 
          {
          msrFrame[saxi][saxj] = iFlipFactors[saxj]*nrrd->measurementFrame[saxi][saxj];
          }
        else
          {
          msrFrame[saxi][saxj] = nrrd->measurementFrame[saxi][saxj];
          }
        }
      }
    EncapsulateMetaData<std::vector<std::vector<double> > >(thisDic,
                                                            std::string(key),
                                                            msrFrame);
    }
  
  nrrd = nrrdNix(nrrd);
  nio = nrrdIoStateNix(nio);
}


void NrrdImageIO::Read(void* buffer)
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 

  Nrrd *nrrd = nrrdNew();
  unsigned int baseDim;
  bool nrrdAllocated;

  // NOTE the main reason the logic becomes complicated here is that
  // ITK has to be the one to allocate the data segment ("buffer")

  if (ImageIOBase::SYMMETRICSECONDRANKTENSOR == this->GetPixelType())
    {
    // It may be that this is coming from a nrrdKind3DMaskedSymMatrix,
    // in which case ITK's buffer has not been allocated for the
    // actual size of the data.  The data will be allocated by nrrdLoad.
    nrrdAllocated = true;
    }
  else 
    {
    // The data buffer has already been allocated for the correct size.
    // Hand the buffer off to the nrrd, setting just enough info so that
    // the nrrd knows the allocated data size (the axes may actually be out
    // of order in the case of non-scalar data.  Internal to nrrdLoad(), the
    // given buffer will be re-used, instead of allocating new data.
    nrrdAllocated = false;
    nrrd->data = buffer;
    nrrd->type = this->ITKToNrrdComponentType( this->m_ComponentType );
    if ( ImageIOBase::SCALAR == this->m_PixelType )
      {
      baseDim = 0;
      }
    else 
      {
      baseDim = 1;
      nrrd->axis[0].size = this->GetNumberOfComponents();
      }
    nrrd->dim = baseDim + this->GetNumberOfDimensions();
    for (unsigned int axi = 0; axi < this->GetNumberOfDimensions(); axi++)
      {
      nrrd->axis[axi+baseDim].size = this->GetDimensions(axi);
      }
    }

  // Read in the nrrd.  Yes, this means that the header is being read
  // twice: once by NrrdImageIO::ReadImageInformation, and once here
  if ( nrrdLoad(nrrd, this->GetFileName(), NULL) != 0 )
    {
    char *err =  biffGetDone(NRRD); // would be nice to free(err)
    itkExceptionMacro("Read: Error reading " 
                      << this->GetFileName() << ":\n" << err);
    }

  unsigned int rangeAxisNum, rangeAxisIdx[NRRD_DIM_MAX];
  rangeAxisNum = nrrdRangeAxesGet(nrrd, rangeAxisIdx);

  if ( rangeAxisNum > 1)
    {
    itkExceptionMacro("Read: handling more than one non-scalar axis "
                      "not currently handled");
    }
  if (1 == rangeAxisNum && 0 != rangeAxisIdx[0])
    {
    // the range (dependent variable) is not on the fastest axis,
    // so we have to permute axes to put it there, since that is
    // how we set things up in ReadImageInformation() above
    Nrrd *ntmp = nrrdNew();
    unsigned int axmap[NRRD_DIM_MAX];
    axmap[0] = rangeAxisIdx[0];
    for (unsigned int axi=1; axi<nrrd->dim; axi++)
      {
      axmap[axi] = axi - (axi <= rangeAxisIdx[0]);
      }
    // The memory size of the input and output of nrrdAxesPermute is
    // the same; the existing nrrd->data is re-used.
    if (nrrdCopy(ntmp, nrrd)
        || nrrdAxesPermute(nrrd, ntmp, axmap))
      {
      char *err =  biffGetDone(NRRD); // would be nice to free(err)
      itkExceptionMacro("Read: Error permuting independent axis in " 
                        << this->GetFileName() << ":\n" << err);
      }
    nrrdNuke(ntmp);
    }

  if (nrrdAllocated)
    {
    // Now we have to get the data back into the given ITK buffer
    // In any case, the logic here has the luxury of assuming that the
    // *single* non-scalar axis is the *first* (fastest) axis.
    if (nrrdKind3DMaskedSymMatrix == nrrd->axis[0].kind
        && ImageIOBase::SYMMETRICSECONDRANKTENSOR == this->GetPixelType())
      {
      // we crop out the mask and put the output in ITK-allocated "buffer"
      size_t size[NRRD_DIM_MAX], minIdx[NRRD_DIM_MAX], maxIdx[NRRD_DIM_MAX];
      for (unsigned int axi=0; axi<nrrd->dim; axi++)
        {
        minIdx[axi] = (0 == axi) ? 1 : 0;
        maxIdx[axi] = nrrd->axis[axi].size-1;
        size[axi] = maxIdx[axi] - minIdx[axi] + 1;
        }
      Nrrd *ntmp = nrrdNew();
      if (nrrdCopy(ntmp, nrrd)
          || (nrrdEmpty(nrrd), 
              nrrdWrap_nva(nrrd, buffer, ntmp->type, ntmp->dim, size))
          || nrrdCrop(nrrd, ntmp, minIdx, maxIdx))
        {
        char *err =  biffGetDone(NRRD); // would be nice to free(err)
        itkExceptionMacro("Read: Error copying, crapping or cropping:\n"
                          << err);
        }
      nrrdNuke(ntmp);
      nrrdNix(nrrd);
      }
    else
      {

      // false alarm; we didn't need to allocate the data ourselves
      memcpy(buffer, nrrd->data,
             nrrdElementSize(nrrd)*nrrdElementNumber(nrrd));
      nrrdNuke(nrrd);
      }
    }
  else // 
    {

    // "buffer" == nrrd->data was ITK-allocated; lose the nrrd struct
    nrrdNix(nrrd);
    }
} 


bool NrrdImageIO::CanWriteFile( const char * name )
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 

  std::string filename = name;
  if(  filename == "" )
    {
    return false;
    }

  std::string::size_type nrrdPos = filename.rfind(".nrrd");
  if ((nrrdPos != std::string::npos)
      && (nrrdPos == filename.length() - 5))
    {
    return true;
    }

  std::string::size_type nhdrPos = filename.rfind(".nhdr");
  if ((nhdrPos != std::string::npos)
      && (nhdrPos == filename.length() - 5))
    {
    return true;
    }

  return false;
}
  
void NrrdImageIO::WriteImageInformation(void)
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 

  // Nothing needs doing here.
}


void NrrdImageIO::Write( const void* buffer) 
{
#if defined(__BORLANDC__) 
// Disable floating point exceptions in Borland 
  _control87(MCW_EM, MCW_EM); 
#endif // defined(__BORLANDC__) 

  Nrrd *nrrd = nrrdNew();
  NrrdIoState *nio = nrrdIoStateNew();
  int kind[NRRD_DIM_MAX];
  size_t size[NRRD_DIM_MAX];
  unsigned int nrrdDim, baseDim, spaceDim;
  double spaceDir[NRRD_DIM_MAX][NRRD_SPACE_DIM_MAX];
  double origin[NRRD_DIM_MAX];

  spaceDim = this->GetNumberOfDimensions();
  if (this->GetNumberOfComponents() > 1)
    {
    size[0] = this->GetNumberOfComponents();
    switch (this->GetPixelType())
      {
      case ImageIOBase::RGB:
        kind[0] = nrrdKindRGBColor;
        break;
      case ImageIOBase::RGBA:
        kind[0] = nrrdKindRGBAColor;
        break;
      case ImageIOBase::POINT:
        kind[0] = nrrdKindPoint;
        break;
      case ImageIOBase::COVARIANTVECTOR:
        kind[0] = nrrdKindCovariantVector;
        break;
      case ImageIOBase::SYMMETRICSECONDRANKTENSOR:
      case ImageIOBase::DIFFUSIONTENSOR3D:
        kind[0] = nrrdKind3DSymMatrix;
        break;
      case ImageIOBase::COMPLEX:
        kind[0] = nrrdKindComplex;
        break;
      case ImageIOBase::VECTOR:
      case ImageIOBase::OFFSET:      // HEY is this right?
      case ImageIOBase::FIXEDARRAY:  // HEY is this right?
      default:
        kind[0] = nrrdKindVector;
        break;
      }
    // the range axis has no space direction
    for (unsigned int saxi=0; saxi < spaceDim; saxi++)
      {
      spaceDir[0][saxi] = AIR_NAN;
      }
    baseDim = 1;
    }
  else
    {
    baseDim = 0;
    }
  nrrdDim = baseDim + spaceDim;
  std::vector<double> spaceDirStd(spaceDim);
  unsigned int axi;
  for (axi=0; axi < spaceDim; axi++)
    {
    size[axi+baseDim] = this->GetDimensions(axi);
    kind[axi+baseDim] = nrrdKindDomain;
    origin[axi] = this->GetOrigin(axi);
    double spacing = this->GetSpacing(axi);
    spaceDirStd = this->GetDirection(axi);
    for (unsigned int saxi=0; saxi < spaceDim; saxi++)
      {
      spaceDir[axi+baseDim][saxi] = spacing*spaceDirStd[saxi];
      }
    }
  if (nrrdWrap_nva(nrrd, const_cast<void *>(buffer),
                   this->ITKToNrrdComponentType( m_ComponentType ),
                   nrrdDim, size) || (3 == spaceDim
       // special case: ITK is LPS in 3-D
       ? nrrdSpaceSet(nrrd, nrrdSpaceLeftPosteriorSuperior)
       : nrrdSpaceDimensionSet(nrrd, spaceDim)) ||
      nrrdSpaceOriginSet(nrrd, origin))
    {
    char *err = biffGetDone(NRRD); // would be nice to free(err)
    itkExceptionMacro("Write: Error wrapping nrrd for " 
                      << this->GetFileName() << ":\n" << err);
    }
  nrrdAxisInfoSet_nva(nrrd, nrrdAxisInfoKind, kind);
  nrrdAxisInfoSet_nva(nrrd, nrrdAxisInfoSpaceDirection, spaceDir);

  // Go through MetaDataDictionary and set either specific nrrd field
  // or a key/value pair
  MetaDataDictionary &thisDic = this->GetMetaDataDictionary();
  std::vector<std::string> keys = thisDic.GetKeys();
  std::vector<std::string>::const_iterator keyIt;
  const char *keyField, *field;
  for( keyIt = keys.begin(); keyIt != keys.end(); keyIt++ )
    {
    if (!strncmp(KEY_PREFIX, (*keyIt).c_str(), strlen(KEY_PREFIX)))
      {
      keyField = (*keyIt).c_str() + strlen(KEY_PREFIX);
      // only of one of these can succeed
      field = airEnumStr(nrrdField, nrrdField_thicknesses);
      if (!strncmp(keyField, field, strlen(field)))
        {
        if (1 == sscanf(keyField + strlen(field), "[%d]", &axi)
            && axi + baseDim < nrrd->dim)
          {
          double thickness = 0.0;  // local for Borland
          ExposeMetaData<double>(thisDic, *keyIt, thickness);
          nrrd->axis[axi+baseDim].thickness = thickness;
          }
        }
      field = airEnumStr(nrrdField, nrrdField_centers);
      if (!strncmp(keyField, field, strlen(field)))
        {
        if (1 == sscanf(keyField + strlen(field), "[%d]", &axi)
            && axi + baseDim < nrrd->dim)
          {
          std::string value;  // local for Borland
          ExposeMetaData<std::string>(thisDic, *keyIt, value);
          nrrd->axis[axi+baseDim].center = airEnumVal(nrrdCenter,
                                                      value.c_str());
          }
        }
      field = airEnumStr(nrrdField, nrrdField_kinds);
      if (!strncmp(keyField, field, strlen(field)))
        {
        if (1 == sscanf(keyField + strlen(field), "[%d]", &axi)
            && axi + baseDim < nrrd->dim)
          {
          std::string value;  // local for Borland
          ExposeMetaData<std::string>(thisDic, *keyIt, value);
          nrrd->axis[axi+baseDim].kind = airEnumVal(nrrdKind,
                                                    value.c_str());
          }
        }
      field = airEnumStr(nrrdField, nrrdField_labels);
      if (!strncmp(keyField, field, strlen(field)))
        {
        if (1 == sscanf(keyField + strlen(field), "[%d]", &axi)
            && axi + baseDim < nrrd->dim)
          {
          std::string value;  // local for Borland
          ExposeMetaData<std::string>(thisDic, *keyIt, value);
          nrrd->axis[axi+baseDim].label = airStrdup(value.c_str());
          }
        }
      field = airEnumStr(nrrdField, nrrdField_old_min);
      if (!strncmp(keyField, field, strlen(field)))
        {
        ExposeMetaData<double>(thisDic, *keyIt, nrrd->oldMin);
        }
      field = airEnumStr(nrrdField, nrrdField_old_max);
      if (!strncmp(keyField, field, strlen(field)))
        {
        ExposeMetaData<double>(thisDic, *keyIt, nrrd->oldMax);
        }

      field = airEnumStr(nrrdField, nrrdField_space);
      if (!strncmp(keyField, field, strlen(field)))
        {
        int space;
        std::string value;  // local for Borland
        ExposeMetaData<std::string>(thisDic, *keyIt, value);
        space = airEnumVal(nrrdSpace, value.c_str());
        if (nrrdSpaceDimension(space) == nrrd->spaceDim)
          {
          // sanity check
          nrrd->space = space;
          }
        }

      field = airEnumStr(nrrdField, nrrdField_content);
      if (!strncmp(keyField, field, strlen(field)))
        {
        std::string value;  // local for Borland
        ExposeMetaData<std::string>(thisDic, *keyIt, value);
        nrrd->content = airStrdup(value.c_str());
        }
      field = airEnumStr(nrrdField, nrrdField_measurement_frame);
      if (!strncmp(keyField, field, strlen(field)))
        {
        std::vector<std::vector<double> > msrFrame;
        ExposeMetaData<std::vector<std::vector<double> > >(thisDic,
                                                           *keyIt, msrFrame);
        for (unsigned int saxi=0; saxi < nrrd->spaceDim; saxi++)
          {
          for (unsigned int saxj=0; saxj < nrrd->spaceDim; saxj++)
            {
            if (saxi < msrFrame.size() &&
                saxj < msrFrame[saxi].size())
              {
              nrrd->measurementFrame[saxi][saxj] = msrFrame[saxi][saxj];
              }
            else
              {
              // there is a difference between the dimension of the 
              // recorded measurement frame, and the actual dimension of
              // the ITK image, which (for now) determines nrrd->spaceDim.
              // We can't set this to AIR_NAN, because the coefficients of
              // the measurement frame have to all be equally existent.
              // If we used 0, it might not a flag that something is wrong.
              // So, we have to get creative.
              nrrd->measurementFrame[saxi][saxj] = 666666;
              }
            }
          }
        }
      }
    else
      {
      // not a NRRD field packed into meta data; just a regular key/value
      std::string value;  // local for Borland
      ExposeMetaData<std::string>(thisDic, *keyIt, value);
      nrrdKeyValueAdd(nrrd, (*keyIt).c_str(), value.c_str());
      }
    }

  // set encoding for data: compressed (raw), (uncompressed) raw, or ascii
  if (this->GetUseCompression() == true
      && nrrdEncodingGzip->available())
    {
    // this is necessarily gzip-compressed *raw* data
    nio->encoding = nrrdEncodingGzip;
    }
  else
    {
    Superclass::FileType fileType = this->GetFileType();
    switch ( fileType )
      {
      default:
      case TypeNotApplicable:
      case Binary:
        nio->encoding = nrrdEncodingRaw;
        break;
      case ASCII:
        nio->encoding = nrrdEncodingAscii;
        break;
      }
    }

  // set desired endianness of output
  Superclass::ByteOrder byteOrder = this->GetByteOrder();
  switch (byteOrder)
    {
    default:
    case OrderNotApplicable:
      nio->endian = airEndianUnknown;
      break;
    case BigEndian:
      nio->endian = airEndianBig;
      break;
    case LittleEndian:
      nio->endian = airEndianLittle;
      break;
    }
  
  // Write the nrrd to file.
  if (nrrdSave(this->GetFileName(), nrrd, nio))
    {
    char *err = biffGetDone(NRRD); // would be nice to free(err)
    itkExceptionMacro("Write: Error writing " 
                      << this->GetFileName() << ":\n" << err);
    }
  
  // Free the nrrd struct but don't touch nrrd->data
  nrrd = nrrdNix(nrrd);
  nio = nrrdIoStateNix(nio);
}
 
} // end namespace itk