Add images to a ggbrain object

Usage

images(images = NULL, volumes = NULL, labels = NULL, filter = NULL)

images: a character vector or ggbrain_images object containing NIfTI images to add to this plot
volumes: a number indicating the volume within the images to display. At present, this must be a single number -- perhaps in the future, it could be a vector so that many timepoints in a 4-D image could be displayed.
labels: a data.frame or named list of data.frame objects corresponding to images that should be labeled. You can only provide a data.frame if there is a single image being added. If multiple images are added, the names of the labels list are used to align the labels with a given matching image.
filter: a named list or character string specifying an expression of values to retain in the image, or a numeric vector of values to retain. Calls ggbrain_images$filter_image()

a ggb object with the relevant images and an action of 'add_images'

  t1 <- system.file("extdata", "mni_template_2009c_3mm.nii.gz", package = "ggbrain")
  gg_obj <- ggbrain() +
    images(c(underlay = t1))