updateNifti {RNifti}R Documentation

Update an internal NIfTI-1 object using a template

Description

This function adds or updates the internal NIfTI-1 object for an array, using metadata from the template. The dimensions and, if available, pixel dimensions, from the image will replace those from the template.

Usage

updateNifti(image, template = NULL, datatype = "auto")

Arguments

image

A numeric array.

template

An image, in any acceptable form (see retrieveNifti), or a named list of NIfTI-1 properties like that produced by niftiHeader. The default of NULL will have no effect.

datatype

The NIfTI datatype to use within the internal image. The default, "auto" uses the R type. Other possibilities are "float", "int16", etc., which may be preferred to reduce object size. However, no checks are done to ensure that the coercion maintains precision, and this option is for advanced usage only.

Details

If template is a complete list of NIfTI-1 header fields, like that produced by niftiHeader, or an image, then it will be used to create the internal object, and then the data and metadata associated with the image will overwrite the appropriate parts. If template is an incomplete list, the image will be used to create the internal object, and then the specified fields will be overwritten from the list. This allows users to selectively update certain fields while leaving others alone (but see the note below).

Datatype information in a list template is ignored. The datatype can only be changed using the datatype argument, but in this case the internal object gets out of sync with the R array, so an internal image is returned to avoid the mismatch. Changing the internal datatype in this way is for advanced usage only.

Value

A copy of the original image, with its internal image attribute set or updated appropriately. If datatype is not "auto" then the result is an internal image.

Note

The scl_slope and scl_inter fields affect the numerical interpretation of the pixel data, so it is impossible in general to change them without also changing the array values on both the C and the R side. Therefore, to avoid unexpected side-effects, these fields are not affected by this function.

Author(s)

Jon Clayden <code@clayden.org>

[Package RNifti version 0.9.0 Index]