diff --git a/DESCRIPTION b/DESCRIPTION
index 157e98f..8b67263 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -42,4 +42,4 @@ Suggests:
     sbtools (>= 0.19.3),
     secret,
     testthat
-RoxygenNote: 6.0.1
+RoxygenNote: 6.1.0
diff --git a/NAMESPACE b/NAMESPACE
index 3ee4f09..c713e70 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -161,14 +161,13 @@ importFrom(grithub,interactive.login)
 importFrom(httr,HEAD)
 importFrom(httr,headers)
 importFrom(httr,parse_http_date)
-importFrom(imager,height)
-importFrom(imager,load.image)
-importFrom(imager,width)
 importFrom(markdown,markdownToHTML)
 importFrom(methods,getPackageName)
+importFrom(png,readPNG)
 importFrom(remotes,install_github)
 importFrom(stats,runif)
 importFrom(stats,setNames)
+importFrom(tools,file_ext)
 importFrom(tools,file_path_sans_ext)
 importFrom(utils,URLencode)
 importFrom(utils,download.file)
diff --git a/R/publish.R b/R/publish.R
index 6a69273..48eaa20 100644
--- a/R/publish.R
+++ b/R/publish.R
@@ -521,16 +521,17 @@ publish.thumbnail <- function(viz){
   required <- c("relpath", "title", "alttext")
   viz <- NextMethod()
   checkRequired(viz, required)
+  stopifnot(tools::file_ext(viz[['location']]) == "png")
   
   im <- tryCatch({
-    imager::load.image(viz[['location']])
+    png::readPNG(viz[['location']])
   },
   error=function(cond){
-    return(imager::load.image(system.file("testviz/images/landing-thumb.png", package = "vizlab")))
+    return(png::readPNG(system.file("testviz/images/landing-thumb.png", package = "vizlab")))
   })
   
-  width <- imager::width(im)
-  height <- imager::height(im)
+  width <- dim(im)[2]
+  height <- dim(im)[1]
   file_size  <- tryCatch({
     file.info(viz[['location']])
   },
@@ -565,11 +566,13 @@ convb <- function(x){
 }
 
 #' helper to check thumbnail compliance
-#' @importFrom imager load.image width height
+#' @importFrom png readPNG
+#' @importFrom tools file_ext
 #' @param width numeric pixal width of image
 #' @param height numeric pixal height of image
 #' @param size numeric file size in bytes
 #' @param thumbType char Type of thumbnail, could be "facebook", "twitter", "landing", "main"
+
 checkThumbCompliance <- function(width, height, size, thumbType){
   
   stopifnot(all(thumbType %in% c("facebook","twitter","main","landing")))