nifti1_io
Public Attributes
nifti_1_header Struct Reference

Data structure defining the fields in the nifti1 header. This binary header should be found at the beginning of a valid NIFTI-1 header file. More...

#include <nifti1.h>

List of all members.

Public Attributes

int sizeof_hdr
char data_type [10]
char db_name [18]
int extents
short session_error
char regular
char dim_info
short dim [8]
float intent_p1
float intent_p2
float intent_p3
short intent_code
short datatype
short bitpix
short slice_start
float pixdim [8]
float vox_offset
float scl_slope
float scl_inter
short slice_end
char slice_code
char xyzt_units
float cal_max
float cal_min
float slice_duration
float toffset
int glmax
int glmin
char descrip [80]
char aux_file [24]
short qform_code
short sform_code
float quatern_b
float quatern_c
float quatern_d
float qoffset_x
float qoffset_y
float qoffset_z
float srow_x [4]
float srow_y [4]
float srow_z [4]
char intent_name [16]
char magic [4]

Detailed Description

Data structure defining the fields in the nifti1 header. This binary header should be found at the beginning of a valid NIFTI-1 header file.

INTRODUCTION TO NIFTI-1: ------------------------ The twin (and somewhat conflicting) goals of this modified ANALYZE 7.5 format are: (a) To add information to the header that will be useful for functional neuroimaging data analysis and display. These additions include:

Most of the unused fields in the ANALYZE 7.5 header have been taken, and some of the lesser-used fields have been co-opted for other purposes. Notably, most of the data_history substructure has been co-opted for other purposes, since the ANALYZE 7.5 format describes this substructure as "not required".

NIFTI-1 FLAG (MAGIC STRINGS): ---------------------------- To flag such a struct as being conformant to the NIFTI-1 spec, the last 4 bytes of the header must be either the C String "ni1" or "n+1"; in hexadecimal, the 4 bytes 6E 69 31 00 or 6E 2B 31 00 (in any future version of this format, the '1' will be upgraded to '2', etc.). Normally, such a "magic number" or flag goes at the start of the file, but trying to avoid clobbering widely-used ANALYZE 7.5 fields led to putting this marker last. However, recall that "the last shall be first" (Matthew 20:16).

If a NIFTI-aware program reads a header file that is NOT marked with a NIFTI magic string, then it should treat the header as an ANALYZE 7.5 structure.

NIFTI-1 FILE STORAGE: -------------------- "ni1" means that the image data is stored in the ".img" file corresponding to the header file (starting at file offset 0).

"n+1" means that the image data is stored in the same file as the header information. We recommend that the combined header+data filename suffix be ".nii". When the dataset is stored in one file, the first byte of image data is stored at byte location (int)vox_offset in this combined file. The minimum allowed value of vox_offset is 352; for compatibility with some software, vox_offset should be an integral multiple of 16.

GRACE UNDER FIRE: ---------------- Most NIFTI-aware programs will only be able to handle a subset of the full range of datasets possible with this format. All NIFTI-aware programs should take care to check if an input dataset conforms to the program's needs and expectations (e.g., check datatype, intent_code, etc.). If the input dataset can't be handled by the program, the program should fail gracefully (e.g., print a useful warning; not crash).

SAMPLE CODES: ------------ The associated files nifti1_io.h and nifti1_io.c provide a sample implementation in C of a set of functions to read, write, and manipulate NIFTI-1 files. The file nifti1_test.c is a sample program that uses the nifti1_io.c functions. -----------------------------------------------------------------------------


Member Data Documentation

auxiliary filename.

Number bits/voxel.

Max display intensity

Min display intensity

++UNUSED++

Defines data type!

++UNUSED++

any text you like.

Data array dimensions.

MRI slice ordering.

++UNUSED++

++UNUSED++

++UNUSED++

NIFTI_INTENT_* code.

'name' or meaning of data.

1st intent parameter.

2nd intent parameter.

3rd intent parameter.

MUST be "ni1\0" or "n+1\0".

Grid spacings.

NIFTI_XFORM_* code.

Quaternion x shift.

Quaternion y shift.

Quaternion z shift.

Quaternion b param.

Quaternion c param.

Quaternion d param.

++UNUSED++

Data scaling: offset.

Data scaling: slope.

++UNUSED++

NIFTI_XFORM_* code.

MUST be 348

Slice timing order.

Time for 1 slice.

Last slice index.

First slice index.

1st row affine transform.

2nd row affine transform.

3rd row affine transform.

Time axis shift.

Offset into .nii file

Units of pixdim[1..4]


The documentation for this struct was generated from the following file:
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