downsample-methods: Downsample an Image

In neuroim2: Data Structures for Brain Imaging Data

Downsample an Image

Description

This function downsamples a neuroimaging object, reducing its spatial resolution while preserving the temporal dimension.

Usage

downsample(x, ...)

## S4 method for signature 'DenseNeuroVec'
downsample(x, spacing = NULL, factor = NULL, outdim = NULL, method = "box")

## S4 method for signature 'SparseNeuroVec'
downsample(x, spacing = NULL, factor = NULL, outdim = NULL, method = "box")

## S4 method for signature 'NeuroVec'
downsample(x, spacing = NULL, factor = NULL, outdim = NULL, method = "box")

## S4 method for signature 'DenseNeuroVol'
downsample(x, spacing = NULL, factor = NULL, outdim = NULL, method = "box")

## S4 method for signature 'NeuroVol'
downsample(x, spacing = NULL, factor = NULL, outdim = NULL, method = "box")

Arguments

x	A DenseNeuroVol object to downsample
...	Additional arguments passed to specific downsample methods.
spacing	Target voxel spacing (numeric vector of length 3)
factor	Downsampling factor (single value or vector of length 3, between 0 and 1)
outdim	Target output dimensions (numeric vector of length 3)
method	Downsampling method (currently only "box" for box averaging)

Value

An object of the same class as x, downsampled according to the specified parameters.

Examples

# Create a sample 4D image
data <- array(rnorm(64*64*32*10), dim = c(64, 64, 32, 10))
space <- NeuroSpace(dim = c(64, 64, 32, 10), 
                    origin = c(0, 0, 0),
                    spacing = c(2, 2, 2))
nvec <- DenseNeuroVec(data, space)

# Downsample by factor
nvec_down1 <- downsample(nvec, factor = 0.5)

# Downsample to target spacing
nvec_down2 <- downsample(nvec, spacing = c(4, 4, 4))

# Downsample to target dimensions
nvec_down3 <- downsample(nvec, outdim = c(32, 32, 16))

# Create a sample 3D volume
data <- array(rnorm(64*64*32), dim = c(64, 64, 32))
space <- NeuroSpace(dim = c(64, 64, 32), 
                    origin = c(0, 0, 0),
                    spacing = c(2, 2, 2))
vol <- DenseNeuroVol(data, space)

# Downsample by factor
vol_down1 <- downsample(vol, factor = 0.5)

# Downsample to target spacing
vol_down2 <- downsample(vol, spacing = c(4, 4, 4))

# Downsample to target dimensions
vol_down3 <- downsample(vol, outdim = c(32, 32, 16))

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