diff --git a/R/layers.R b/R/layers.R
index 1bead2d20..0a589b9d9 100644
--- a/R/layers.R
+++ b/R/layers.R
@@ -209,6 +209,10 @@ epsg3857 <- "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y
 #'   the caller's responsibility to ensure that \code{x} is already projected,
 #'   and that \code{extent(x)} is expressed in WGS84 latitude/longitude
 #'   coordinates
+#' @param method the method used for computing values of the new, projected raster image.
+#'   \code{"bilinear"} (the default) is appropriate for continuous data,
+#'   \code{"ngb"} - nearest neighbor - is appropriate for categorical data.
+#'   Ignored if \code{project = FALSE}. See \code{\link{projectRaster}} for details.
 #' @param maxBytes the maximum number of bytes to allow for the projected image
 #'   (before base64 encoding); defaults to 4MB.
 #'
@@ -231,12 +235,14 @@ addRasterImage <- function(
   layerId = NULL,
   group = NULL,
   project = TRUE,
+  method = c("bilinear", "ngb"),
   maxBytes = 4*1024*1024
 ) {
   stopifnot(inherits(x, "RasterLayer"))
 
   if (project) {
-    projected <- projectRasterForLeaflet(x)
+    method <- match.arg(method, c("bilinear", "ngb"))
+    projected <- projectRasterForLeaflet(x, method)
   } else {
     projected <- x
   }
@@ -266,8 +272,12 @@ addRasterImage <- function(
 
 #' @rdname addRasterImage
 #' @export
-projectRasterForLeaflet <- function(x) {
-  raster::projectRaster(x, raster::projectExtent(x, crs = sp::CRS(epsg3857)))
+projectRasterForLeaflet <- function(x, method) {
+  raster::projectRaster(
+    x,
+    raster::projectExtent(x, crs = sp::CRS(epsg3857)),
+    method = method
+  )
 }
 
 #' @rdname remove
diff --git a/R/leaflet.R b/R/leaflet.R
index 427f81c29..8841f6801 100644
--- a/R/leaflet.R
+++ b/R/leaflet.R
@@ -21,12 +21,15 @@
 #' @param height the height of the map
 #' @param padding the padding of the map
 #' @param options the map options
+#' @param elementId Use an explicit element ID for the widget
+#'   (rather than an automatically generated one).
 #' @return A HTML widget object, on which we can add graphics layers using
 #'   \code{\%>\%} (see examples).
 #' @example inst/examples/leaflet.R
 #' @export
 leaflet <- function(data = NULL, width = NULL, height = NULL,
-                   padding = 0, options = leafletOptions()) {
+                   padding = 0, options = leafletOptions(),
+                   elementId = NULL) {
 
   # Validate the CRS if specified
   if(!is.null(options[['crs']]) &&
@@ -61,7 +64,8 @@ leaflet <- function(data = NULL, width = NULL, height = NULL,
         })
       }
       widget
-    }
+    },
+    elementId = elementId
   )
 
   if (crosstalk::is.SharedData(data)) {
diff --git a/man/addRasterImage.Rd b/man/addRasterImage.Rd
index d51a95d3f..851afdecc 100644
--- a/man/addRasterImage.Rd
+++ b/man/addRasterImage.Rd
@@ -7,9 +7,9 @@
 \usage{
 addRasterImage(map, x, colors = "Spectral", opacity = 1,
   attribution = NULL, layerId = NULL, group = NULL, project = TRUE,
-  maxBytes = 4 * 1024 * 1024)
+  method = c("bilinear", "ngb"), maxBytes = 4 * 1024 * 1024)
 
-projectRasterForLeaflet(x)
+projectRasterForLeaflet(x, method)
 }
 \arguments{
 \item{map}{a map widget object}
@@ -35,6 +35,11 @@ the caller's responsibility to ensure that \code{x} is already projected,
 and that \code{extent(x)} is expressed in WGS84 latitude/longitude
 coordinates}
 
+\item{method}{the method used for computing values of the new, projected raster image.
+\code{"bilinear"} (the default) is appropriate for continuous data,
+\code{"ngb"} - nearest neighbor - is appropriate for categorical data.
+Ignored if \code{project = FALSE}. See \code{\link{projectRaster}} for details.}
+
 \item{maxBytes}{the maximum number of bytes to allow for the projected image
 (before base64 encoding); defaults to 4MB.}
 }
diff --git a/man/leaflet.Rd b/man/leaflet.Rd
index e27097d3e..98f4df6b6 100644
--- a/man/leaflet.Rd
+++ b/man/leaflet.Rd
@@ -7,7 +7,7 @@
 \title{Create a Leaflet map widget}
 \usage{
 leaflet(data = NULL, width = NULL, height = NULL, padding = 0,
-  options = leafletOptions())
+  options = leafletOptions(), elementId = NULL)
 
 leafletOptions(minZoom = NULL, maxZoom = NULL, crs = leafletCRS(),
   worldCopyJump = NULL, ...)
@@ -33,6 +33,9 @@ spatial data frames from the \pkg{sf} package.}
 
 \item{options}{the map options}
 
+\item{elementId}{Use an explicit element ID for the widget
+(rather than an automatically generated one).}
+
 \item{minZoom}{Minimum zoom level of the map. Overrides any minZoom set on map layers.}
 
 \item{maxZoom}{Maximum zoom level of the map. This overrides any maxZoom set on map layers.}