diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index c5e30040..6269372d 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -65,6 +65,11 @@ jobs:
           sysreqs=$(Rscript -e "cat(sysreqs::sysreq_commands('DESCRIPTION'))")
           sudo -s eval "$sysreqs"
 
+      - name: Install pngquant
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-get install -y pngquant
+
       - name: Install dependencies
         run: |
           remotes::install_deps(dependencies = TRUE)
diff --git a/vignettes/children/chunk_options.txt b/vignettes/children/chunk_options.txt
index 27924968..b3801f61 100755
--- a/vignettes/children/chunk_options.txt
+++ b/vignettes/children/chunk_options.txt
@@ -8,7 +8,10 @@ img {
 </style>
 
 ```{r chunk_options, include=FALSE}
-if (requireNamespace("pkgdown", quietly = TRUE) && pkgdown::in_pkgdown()) {
+in_pkgdown = requireNamespace("pkgdown", quietly = TRUE) && pkgdown::in_pkgdown()
+
+# image dimensions
+if (in_pkgdown) {
   tiny_width = 5.5
   tiny_height = 3 + 2/3
   small_width = med_width = 6.75
@@ -25,12 +28,13 @@ if (requireNamespace("pkgdown", quietly = TRUE) && pkgdown::in_pkgdown()) {
   large_width = 5.5
   large_height = 2/3
 }
-
 knitr::opts_chunk$set(
   fig.width = small_width,
   fig.height = small_height
 )
-if (requireNamespace("ragg", quietly = TRUE)) {
+
+# graphics device
+if (requireNamespace("ragg", quietly = TRUE) && in_pkgdown) {
   knitr::opts_chunk$set(
     dev = "ragg_png"
   )
@@ -40,4 +44,10 @@ if (requireNamespace("ragg", quietly = TRUE)) {
     dev.args = list(type = "cairo")
   )
 }
+
+# png compression for CRAN
+if (!in_pkgdown) {
+  knitr::knit_hooks$set(pngquant = knitr::hook_pngquant)
+  knitr::opts_chunk$set(pngquant = "--speed=1 --quality=50")
+}
 ```