as_canonical: Reorient Image to Canonical (RAS+) Orientation

In neuroim2: Data Structures for Brain Imaging Data

Reorient Image to Canonical (RAS+) Orientation

Description

Reorients a neuroimaging volume or vector to the canonical RAS+ (Right-Anterior-Superior) orientation by permuting and flipping axes. This is equivalent to nibabel's as_closest_canonical().

Usage

as_canonical(x, target = c("R", "A", "S"))

Arguments

x	A NeuroVol or NeuroVec object.
target	Character vector of length 3 giving the desired orientation. Default is c("R", "A", "S") (RAS+).

Details

The function works by computing the orientation transform from the current axis codes to the target codes, then applying the necessary axis permutations and flips. The affine matrix is updated to reflect the new orientation while preserving world-coordinate mapping.

Value

A reoriented object of the same class as x.

See Also

axcodes, reorient

Examples

sp <- NeuroSpace(c(10L, 10L, 10L), c(2, 2, 2))
vol <- DenseNeuroVol(array(rnorm(1000), c(10,10,10)), sp)
ras_vol <- as_canonical(vol)
axcodes(ras_vol)  # "R" "A" "S"

neuroim2 documentation built on April 16, 2026, 5:07 p.m.