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NIfTI-1 Fields

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nifti-1 header field-by-field documentation

The field-by-field documentation on these pages was taken directly from the official nifti-1 header file documentation written by Bob Cox, SSCC, NIMH. These pages provide a "clickable" index to that information, and some links to additional information.

struct nifti_1_header

                          /**********************/    /**********************/     /***************/
struct nifti_1_header {
/* NIFTI-1 usage */ /*ANALYZE 7.5 field(s)*/ /* Byte offset */
/**********************/ /**********************/ /***************/



int sizeof_hdr; /*!< MUST be 348 */ /* int sizeof_hdr; */ /* 0 */

char data_type[10]; /*!< ++UNUSED++ */ /* char data_type[10]; */ /* 4 */

char db_name[18]; /*!< ++UNUSED++ */ /* char db_name[18]; */ /* 14 */

int extents; /*!< ++UNUSED++ */ /* int extents; */ /* 32 */

short session_error; /*!< ++UNUSED++ */ /* short session_error; */ /* 36 */

char regular; /*!< ++UNUSED++ */ /* char regular; */ /* 38 */

char dim_info; /*!< MRI slice ordering. */ /* char hkey_un0; */ /* 39 */

/*--- was image_dimension substruct ---*/
short dim[8]; /*!< Data array dimensions.*/ /* short dim[8]; */ /* 40 */
float intent_p1; /*!< 1st intent parameter. */ /* short unused8; */ /* 56 */
/* short unused9; */
float intent_p2; /*!< 2nd intent parameter. */ /* short unused10; */ /* 60 */
/* short unused11; */
float intent_p3; /*!< 3rd intent parameter. */ /* short unused12; */ /* 64 */
/* short unused13; */
short intent_code; /*!< NIFTIINTENT code. */ /* short unused14; */ /* 68 */
short datatype; /*!< Defines data type! */ /* short datatype; */ /* 70 */
short bitpix; /*!< Number bits/voxel. */ /* short bitpix; */ /* 72 */
short slice_start; /*!< First slice index. */ /* short dim_un0; */ /* 74 */
float pixdim[8]; /*!< Grid spacings. */ /* float pixdim[8]; */ /* 76 */
float vox_offset; /*!< Offset into .nii file */ /* float vox_offset; */ /* 108 */
float scl_slope; /*!< Data scaling: slope. */ /* float funused1; */ /* 112 */
float scl_inter; /*!< Data scaling: offset. */ /* float funused2; */ /* 116 */
short slice_end; /*!< Last slice index. */ /* float funused3; */ /* 120 */
char slice_code; /*!< Slice timing order. */ /* 122 */
char xyzt_units; /*!< Units of pixdim[1..4] */ /* 123 */
float cal_max; /*!< Max display intensity */ /* float cal_max; */ /* 124 */
float cal_min; /*!< Min display intensity */ /* float cal_min; */ /* 128 */
float slice_duration;/*!< Time for 1 slice. */ /* float compressed; */ /* 132 */
float toffset; /*!< Time axis shift. */ /* float verified; */ /* 136 */
int glmax; /*!< ++UNUSED++ */ /* int glmax; */ /* 140 */
int glmin; /*!< ++UNUSED++ */ /* int glmin; */ /* 144 */

/*--- was data_history substruct ---*/
char descrip[80]; /*!< any text you like. */ /* char descrip[80]; */ /* 148 */
char aux_file[24]; /*!< auxiliary filename. */ /* char aux_file[24]; */ /* 228 */




short qform_code; /*!< NIFTIXFORM code. */ /*-- all ANALYZE 7.5 ---*/ /* 252 */
short sform_code; /*!< NIFTIXFORM code. */ /* fields below here */ /* 254 */
/* are replaced */
float quatern_b; /*!< Quaternion b param. */ /* 256 */
float quatern_c; /*!< Quaternion c param. */ /* 260 */
float quatern_d; /*!< Quaternion d param. */ /* 264 */
float qoffset_x; /*!< Quaternion x shift. */ /* 268 */
float qoffset_y; /*!< Quaternion y shift. */ /* 272 */
float qoffset_z; /*!< Quaternion z shift. */ /* 276 */


float srow_x[4]; /*!< 1st row affine transform. */ /* 280 */
float srow_y[4]; /*!< 2nd row affine transform. */ /* 296 */
float srow_z[4]; /*!< 3rd row affine transform. */ /* 312 */


char intent_name[16];/*!< name or meaning of data. */ /* 328 */


char magic[4]; /*!< MUST be "ni1\0" or "n+1\0". */ /* 344 */



} ; /** 348 bytes total **/


Extension Mechanism

struct nifti1_extender { 
char extension[4] ; /* 348 */
} ;

extension #1
struct nifti1_extension { /* Data structure defining the fields of a header extension. */
int esize; /* 352 */
int ecode ; /* 356 */
char edata ; /* 360 */
} ;


extension #2
struct nifti1_extension { /* Data structure defining the fields of a header extension. */
int esize; /* 352 + esize #1 */
int ecode ;
char *edata ;
} ;


extension #3
struct nifti1_extension { /* Data structure defining the fields of a header extension. */
int esize; /* 352 + esize #1 + esize #2 */
int ecode ;
char *edata ;
} ;


and so on...

Created by Alex Clark
Last modified 2005-05-17 18:43
 

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