make_nii.m

Matlab实现NIfTI(ANALYZE)核磁共振图像读取保存制作 Tools for NIfTI (ANALYZE) MR image 这个Matlab程序包用于处理核磁共振图像

%  Make nii structure specified by 3D matrix [x y z]. It also takes
%  4D matrix like [x y z t]. Optional features can also be included, 
%  such as: voxel_size, origin, datatype, and description.
%  
%  Usage: nii = make_nii(img, [voxel_size], [origin], [datatype], ...
%		[description])
%
%  Where:
%
%	img:			3D matrix [x y z], or 4D matrix that
%				includes all the images along the
%				time course [x y z t]
%
%	voxel_size (optional):	Voxel size in millimeter for each
%				dimension. Default is [1 1 1].
%
%	origin (optional):	The AC origin. Default is [0 0 0].
%
%	datatype (optional):	Storage data type. Default is float32 [16]:
%		2 - uint8,  4 - int16,  8 - int32,  16 - float32,
%		32 - complex64,  64 - float64,  128 - RGB24,
%		256 - int8,  512 - uint16,  768 - uint32, 1792 - complex128
%
%	description (optional):	Description of data. Default is ''.
%
%  e.g.:
%     origin = [33 44 13]; datatype = 64;
%     nii = make_nii(img, [], origin, datatype);    % default voxel_size
%
%  NIFTI data format can be found on: http://nifti.nimh.nih.gov
%
%  - Jimmy Shen ([e-mail])
%
function nii = make_nii(varargin)

   nii.img = varargin{1};
   dims = size(nii.img);
   dims = [length(dims) dims ones(1,8)];
   dims = dims(1:8);

   voxel_size = [0 ones(1,7)];
   origin = zeros(1,5);
   datatype = 16;
   descrip = '';

   if nargin > 1 & ~isempty(varargin{2})
      voxel_size(2:4) = double(varargin{2});
   end

   if nargin > 2 & ~isempty(varargin{3})
      origin(1:3) = double(varargin{3});
   end

   if nargin > 3 & ~isempty(varargin{4})
      datatype = double(varargin{4});
   end

   if nargin > 4 & ~isempty(varargin{5})
      descrip = varargin{5};
   end

   %MPH: Fix dims in the case of RGB datatype
   %
   if datatype == 128
     dims(1) = dims(1)-1;
     dims(5:8) = [dims(6:8) 1];
   end

   maxval = round(double(max(nii.img(:))));
   minval = round(double(min(nii.img(:))));

   nii.hdr = make_header(dims, voxel_size, origin, datatype, ...
	descrip, maxval, minval);

   switch nii.hdr.dime.datatype
   case 2
      nii.img = uint8(nii.img);
   case 4
      nii.img = int16(nii.img);
   case 8
      nii.img = int32(nii.img);
   case 16
      nii.img = single(nii.img);
   case 32
      nii.img = single(nii.img);
   case 64
      nii.img = double(nii.img);
   case 128
      nii.img = uint8(nii.img);
   case 256
      nii.img = int8(nii.img);
   case 512
      nii.img = uint16(nii.img);
   case 768
      nii.img = uint32(nii.img);
   case 1792
      nii.img = double(nii.img);
   otherwise
      error('Datatype is not supported by make_nii.');
   end

   return;					% make_nii


%---------------------------------------------------------------------
function hdr = make_header(dims, voxel_size, origin, datatype, ...
	descrip, maxval, minval)

   hdr.hk   = header_key;
   hdr.dime = image_dimension(dims, voxel_size, datatype, maxval, minval);
   hdr.hist = data_history(origin, descrip);
    
   return;					% make_header


%---------------------------------------------------------------------
function hk = header_key

    hk.sizeof_hdr       = 348;			% must be 348!
    hk.data_type        = '';
    hk.db_name          = '';
    hk.extents          = 0;
    hk.session_error    = 0;
    hk.regular          = 'r';
    hk.dim_info         = 0;
    
    return;					% header_key


%---------------------------------------------------------------------
function dime = image_dimension(dims, voxel_size, datatype, maxval, minval)
   
   dime.dim = dims;
   dime.intent_p1 = 0;
   dime.intent_p2 = 0;
   dime.intent_p3 = 0;
   dime.intent_code = 0;
   dime.datatype = datatype;
   
   switch dime.datatype
   case   2,
      dime.bitpix = 8;  precision = 'uint8';
   case   4,
      dime.bitpix = 16; precision = 'int16';
   case   8,
      dime.bitpix = 32; precision = 'int32';
   case  16,
      dime.bitpix = 32; precision = 'float32';
   case  32,
      dime.bitpix = 64; precision = 'float32';
   case  64,
      dime.bitpix = 64; precision = 'float64';
   case  128,
      dime.bitpix = 24; precision = 'uint8';
   case 256 
      dime.bitpix = 8;  precision = 'int8';
   case 512 
      dime.bitpix = 16; precision = 'uint16';
   case 768 
      dime.bitpix = 32; precision = 'uint32';
   case  1792,
      dime.bitpix = 128; precision = 'float64';
   otherwise
      error('Datatype is not supported by make_nii.');
   end
   
   dime.slice_start = 0;
   dime.pixdim = voxel_size;
   dime.vox_offset = 0;
   dime.scl_slope = 0;
   dime.scl_inter = 0;
   dime.slice_end = 0;
   dime.slice_code = 0;
   dime.xyzt_units = 0;
   dime.cal_max = 0;
   dime.cal_min = 0;
   dime.slice_duration = 0;
   dime.toffset = 0;
   dime.glmax = maxval;
   dime.glmin = minval;
   
   return;					% image_dimension


%---------------------------------------------------------------------
function hist = data_history(origin, descrip)
   
   hist.descrip = descrip;
   hist.aux_file = 'none';
   hist.qform_code = 0;
   hist.sform_code = 0;
   hist.quatern_b = 0;
   hist.quatern_c = 0;
   hist.quatern_d = 0;
   hist.qoffset_x = 0;
   hist.qoffset_y = 0;
   hist.qoffset_z = 0;
   hist.srow_x = zeros(1,4);
   hist.srow_y = zeros(1,4);
   hist.srow_z = zeros(1,4);
   hist.intent_name = '';
   hist.magic = '';
   hist.originator = origin;
   
   return;					% data_history