#' Create CT Head Mask

#'

#' @param img CT image of class \code{\link{nifti}}

#' @param fill_size Size of fill (in voxels),

#' passed to \code{\link[extrantsr]{filler}}

#'

#' @return An object of class \code{\link{nifti}}

#' @export

create_ct_head_mask = function(img, fill_size = 11) {

  img = neurobase::check_nifti(img)

  head_mask = img >= -100 & img <= 1000

  cc = extrantsr::largest_component(head_mask)

  filled = extrantsr::filler(cc, fill_size = fill_size)

  return(filled)

}

#' @export

#' @rdname create_ct_head_mask

segment_ct_head = function(img, fill_size = 11) {

  img = neurobase::check_nifti(img)

  mask = create_ct_head_mask(img, fill_size = fill_size)

  head_img = neurobase::mask_img(img + 1024, mask)

  head_img = head_img - 1024

  return(img)

}