Operations on multi-channel images

[muschellij2]

Need to extend scalars to vector of same length for multi-channel images:

library(ANTsRCore)
#> 
#> Attaching package: 'ANTsRCore'
#> The following objects are masked from 'package:stats':
#> 
#>     sd, var
#> The following objects are masked from 'package:base':
#> 
#>     all, any, apply, max, min, prod, range, sum
fname = system.file("extdata", "multi_component_image.nii.gz", package="ANTsRCore")
img = ANTsRCore::antsImageRead(fname)
img > 0
#> Invalid S4 object type in itk::Image<float,2>::Pointer Rcpp::as()
#> [1] NA
img > c(0, 0)
#> antsImage
#>   Pixel Type          : float 
#>   Components Per Pixel: 3 
#>   Dimensions          : 30x30 
#>   Voxel Spacing       : 1xNA 
#>   Origin              : 0 NA 
#>   Direction           : 1 0 0 1

^{Created on 2019-06-19 by the reprex package (v0.3.0)}