`meta_info()` provides a simple, CRAN-friendly way to retrieve essential image metadata without teaching S4 details up front. It accepts a file path or a `FileMetaInfo` object and returns a normalized list containing common fields like dimensions, spacing, origin, and transform.
The function does not read image data; it only parses header information.
Usage
meta_info(x)
# S4 method for class 'FileMetaInfo'
meta_info(x)
# S4 method for class 'character'
meta_info(x)Arguments
- x
A character file path (e.g., `"image.nii.gz"`) or an object of class
FileMetaInfo.
Value
A named list with the following elements:
`dim` Integer vector of image dimensions.
`spacing` Numeric voxel spacing (mm).
`origin` Numeric coordinate origin.
`trans` 4x4 transformation matrix mapping grid to world (mm).
`path` Data file path.
`filename` Basename of `path`.
`format` File format label (e.g., "NIFTI", "AFNI").
`dtype` Storage data type label.
`bytes_per_element` Bytes per element.
`nvox` Number of voxels in the spatial volume (prod of first 3 dims).
`nvol` Number of volumes (4th dim if present, else 1).
`size_bytes` Approximate uncompressed size in bytes (`nvox * nvol * bytes_per_element`).
`time_step` Time step (TR in seconds) if available for NIfTI, else `NA_real_`.
Examples
# \donttest{
f <- system.file("extdata", "global_mask_v4.nii", package = "neuroim2")
mi <- meta_info(f)
mi$dim
#> [1] 64 64 25 4
mi$spacing
#> [1] 3.5 3.5 3.7
mi$origin
#> [1] 112.0 -108.0 -46.2
mi$filename
#> [1] "global_mask_v4.nii"
# 4x4 transform
mi$trans
#> [,1] [,2] [,3] [,4]
#> [1,] -3.5 0.0 0.0 112.0
#> [2,] 0.0 3.5 0.0 -108.0
#> [3,] 0.0 0.0 3.7 -46.2
#> [4,] 0.0 0.0 0.0 1.0
# }