R/resampleImageToTarget.R

In ANTsX/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

#' resampleImageToTarget
#'
#' Resample image by using another image as target reference.
#' This function uses antsApplyTransform with an identity
#' matrix to achieve proper resampling.
#'
#' @param image image to resample
#' @param target image of reference, the output will be in this space
#' @param interpType Choice of interpolator. Supports partial matching.
#' \describe{
#' \item{linear}{}
#' \item{nearestNeighbor}{}
#' \item{multiLabel}{ for label images but genericlabel is preferred}
#' \item{gaussian}{}
#' \item{bSpline}{}
#' \item{cosineWindowedSinc}{}
#' \item{welchWindowedSinc}{}
#' \item{hammingWindowedSinc}{}
#' \item{lanczosWindowedSinc}{}
#' \item{genericLabel}{ use this for label images}
#' }
#' @param imagetype choose 0/1/2/3 mapping to scalar/vector/tensor/time-series
#' @param verbose print command and run verbose application of transform.
#' @param ... additional arugment passed to \code{antsApplyTransforms} C code
#' @return output antsImage resampled with target's resolution/origin/orientation/direction
#' @author Pustina D
#' @examples
#'
#' fname <- getANTsRData("r16")
#' fi <- antsImageRead(fname)
#' fi2mm <- resampleImage(fi, c(2, 2), useVoxels = 0, interpType = "linear")
#' resampled <- resampleImageToTarget(fi2mm, fi)
#' testthat::expect_error(resampleImageToTarget(fi2mm))
#'
#' @export resampleImageToTarget
#'
resampleImageToTarget <- function(image, target, interpType = "linear",
                                  imagetype = 0, verbose = FALSE, ...) {
  if (missing(image) | missing(target)) {
    stop("missing input image or missing target")
  }
  image <- check_ants(image)
  target <- check_ants(target)
  if (image@components > 1 | target@components > 1) {
    stop("Either input image or target has >1 channel/component pixels; please splitChannels before running this code.")
  }

  fixed <- target
  moving <- image
  compose <- NA
  transformlist <- "identity"
  interpolator <- interpType

  ## compatibility with previous version's integer interpolator
  interpolator.oldoptions <- c(
    "linear", "nearestNeighbor",
    "gaussian", "cosineWindowedSinc", "bSpline"
  )
  if (is.numeric(interpolator)) {
    interpolator <- interpolator.oldoptions[interpolator + 1]
  }
  ### end compatibility

  interpolator[1] <- paste(tolower(substring(
    interpolator[1],
    1, 1
  )), substring(interpolator[1], 2), sep = "", collapse = " ")
  interpOpts <- c(
    "linear", "nearestNeighbor", "multiLabel",
    "gaussian", "bSpline", "cosineWindowedSinc", "welchWindowedSinc",
    "hammingWindowedSinc", "lanczosWindowedSinc", "genericLabel"
  )
  interpolator <- match.arg(interpolator, interpOpts)
  args <- list(
    fixed, moving, transformlist, interpolator,
    ...
  )
  if (!is.character(fixed)) {
    fixed <- check_ants(fixed)
    moving <- check_ants(moving)
    if (fixed@class[[1]] == "antsImage" & moving@class[[1]] ==
      "antsImage") {
      inpixeltype <- fixed@pixeltype
      warpedmovout <- antsImageClone(moving)
      f <- fixed
      m <- moving
      if ((moving@dimension == 4) & (fixed@dimension == 3) & (imagetype == 0)) stop("Set imagetype 3 to transform time series images.")
      wmo <- warpedmovout
      mytx <- list("-t", "identity")

      if (is.na(compose)) {
        args <- list(
          d = fixed@dimension, i = m, o = wmo,
          r = f, n = interpolator, unlist(mytx)
        )
      }
      tfn <- paste(compose, "comptx.nii.gz", sep = "")
      if (!is.na(compose)) {
        mycompo <- paste("[", tfn, ",1]", sep = "")
        args <- list(
          d = fixed@dimension, i = m, o = mycompo,
          r = f, n = interpolator, unlist(mytx)
        )
      }
      myargs <- .int_antsProcessArguments(c(args))
      for (jj in c(1:length(myargs))) {
        if (!is.na(myargs[jj])) {
          if (myargs[jj] == "-") {
            myargs2 <- rep(NA, (length(myargs) - 1))
            myargs2[1:(jj - 1)] <- myargs[1:(jj - 1)]
            myargs2[jj:(length(myargs) - 1)] <- myargs[(jj +
              1):(length(myargs))]
            myargs <- myargs2
          }
        }
      }
      myverb <- as.numeric(verbose)
      if (verbose) {
        print(myargs)
      }
      ANTsRCore::AntsApplyTransforms(c(
        myargs, "-z", 1, "-v",
        myverb, "--float", 1, "-e", imagetype
      ))
      if (is.na(compose)) {
        return(antsImageClone(warpedmovout, inpixeltype))
      }
      if (!is.na(compose)) {
        if (file.exists(tfn)) {
          return(tfn)
        } else {
          return(NA)
        }
      }
    }
    return(1)
  }
  ANTsRCore::AntsApplyTransforms(
    .int_antsProcessArguments(
      c(args, "-z", 1, "--float", 1, "-e", imagetype)
    )
  )
}