R: Pixel dimensions and units

pixdim {RNifti} | R Documentation

## Pixel dimensions and units

### Description

By default, these generic functions return or replace the `"pixdim"` and `"pixunits"` attributes of their arguments. These represent the physical step size between pixel or voxel centre points, and the spatial and temporal units that they are given in. The former defaults to 1 in each dimension, if there is no attribute.

### Usage

    pixdim(object)

    ## Default S3 method:
    pixdim(object)

    pixdim(object) <- value

    ## Default S3 replacement method:
    pixdim(object) <- value

    pixunits(object)

    ## Default S3 method:
    pixunits(object)

    pixunits(object) <- value

    ## Default S3 replacement method:
    pixunits(object) <- value

### Arguments

`object` | An R object, generally an image.
`value` | Numeric vector of pixel dimensions along each axis, or character vector of abbreviated units. For dimensions, a scalar `value` will be recycled if necessary.

### Value

`pixdim` returns a numeric vector of pixel dimensions. `pixunits` returns a character vector of length up to two, giving the spatial and temporal unit names.

### Author(s)

Jon Clayden <code@clayden.org>

### Examples

    im <- readNifti(system.file("extdata", "example.nii.gz", package="RNifti"))
    pixdim(im)
    pixunits(im)

[Package RNifti version 1.2.3 Index]