intent_code

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  • dim intent_p1,2,3 intent_name

nifti1.h header documentation

/---------------------------------------------------------------------------/
/* INTERPRETATION OF VOXEL DATA:
   ----------------------------
   The intent_code field can be used to indicate that the voxel data has
   some particular meaning.  In particular, a large number of codes is
   given to indicate that the the voxel data should be interpreted as
   being drawn from a given probability distribution.
   VECTOR-VALUED DATASETS:
   ----------------------
   The 5th dimension of the dataset, if present (i.e., dim[0]=5 and
   dim[5] > 1), contains multiple values (e.g., a vector) to be stored
   at each spatiotemporal location.  For example, the header values
    - dim[0] = 5
    - dim[1] = 64
    - dim[2] = 64
    - dim[3] = 20
    - dim[4] = 1     (indicates no time axis)
    - dim[5] = 3
    - datatype = DT_FLOAT
    - intent_code = NIFTI_INTENT_VECTOR
   mean that this dataset should be interpreted as a 3D volume (64x64x20),
   with a 3-vector of floats defined at each point in the 3D grid.
   A program reading a dataset with a 5th dimension may want to reformat
   the image data to store each voxels' set of values together in a struct
   or array.  This programming detail, however, is beyond the scope of the
   NIFTI-1 file specification!  Uses of dimensions 6 and 7 are also not
   specified here.
   STATISTICAL PARAMETRIC DATASETS (i.e., SPMs):
   --------------------------------------------
   Values of intent_code from NIFTI_FIRST_STATCODE to NIFTI_LAST_STATCODE
   (inclusive) indicate that the numbers in the dataset should be interpreted
   as being drawn from a given distribution.  Most such distributions have
   auxiliary parameters (e.g., NIFTI_INTENT_TTEST has 1 DOF parameter).
   If the dataset DOES NOT have a 5th dimension, then the auxiliary parameters
   are the same for each voxel, and are given in header fields intent_p1,
   intent_p2, and intent_p3.
   If the dataset DOES have a 5th dimension, then the auxiliary parameters
   are different for each voxel.  For example, the header values
    - dim[0] = 5
    - dim[1] = 128
    - dim[2] = 128
    - dim[3] = 1      (indicates a single slice)
    - dim[4] = 1      (indicates no time axis)
    - dim[5] = 2
    - datatype = DT_FLOAT
    - intent_code = NIFTI_INTENT_TTEST
   mean that this is a 2D dataset (128x128) of t-statistics, with the
   t-statistic being in the first "plane" of data and the degrees-of-freedom
   parameter being in the second "plane" of data.
   If the dataset 5th dimension is used to store the voxel-wise statistical
   parameters, then dim[5] must be 1 plus the number of parameters required
   by that distribution (e.g., intent_code=NIFTI_INTENT_TTEST implies dim[5]
   must be 2, as in the example just above).
   Note: intent_code values 2..10 are compatible with AFNI 1.5x (which is
   why there is no code with value=1, which is obsolescent in AFNI).
   OTHER INTENTIONS:
   ----------------
   The purpose of the intent_* fields is to help interpret the values
   stored in the dataset.  Some non-statistical values for intent_code
   and conventions are provided for storing other complex data types.
   The intent_name field provides space for a 15 character (plus 0 byte)
   name string for the type of data stored. Examples:
    - intent_code = NIFTI_INTENT_ESTIMATE; intent_name = "T1";
       could be used to signify that the voxel values are estimates of the
       NMR parameter T1.
    - intent_code = NIFTI_INTENT_TTEST; intent_name = "House";
       could be used to signify that the voxel values are t-statistics
       for the significance of activation response to a House stimulus.
    - intent_code = NIFTI_INTENT_DISPVECT; intent_name = "ToMNI152";
       could be used to signify that the voxel values are a displacement
       vector that transforms each voxel (x,y,z) location to the
       corresponding location in the MNI152 standard brain.
    - intent_code = NIFTI_INTENT_SYMMATRIX; intent_name = "DTI";
       could be used to signify that the voxel values comprise a diffusion
       tensor image.
   If no data name is implied or needed, intent_name[0] should be set to 0.

DEFINED CODES