Improved the KB about image scaling from CLI

knowledge base/imagemagick.md

@@ -31,5 +31,7 @@ magick *.png out.pdf
 ## Sources
 
 - [Converting Multiple Images into a PDF File]
+- [How to Quickly Resize, Convert & Modify Images from the Linux Terminal]
 
 [converting multiple images into a pdf file]: https://legacy.imagemagick.org/discourse-server/viewtopic.php?p=144157&sid=e7706233f81874af86ffbbf3e57b1e76#p144157
+[how to quickly resize, convert & modify images from the linux terminal]: https://www.howtogeek.com/109369/how-to-quickly-resize-convert-modify-images-from-the-linux-terminal/

knowledge base/resize an image from cli.md

@@ -0,0 +1,16 @@
+# Resize images using the CLI
+
+Leverages `convert` from `imagemagick`.
+
+```sh
+convert input.jpg -adaptive-resize 50% output.jpg
+
+# Scale down all images in a folder.
+ls -1 | xargs -I{} convert {} -adaptive-resize 50% {}_scaled.jpg
+```
+
+Further readings
+
+- [imagemagick]
+
+[imagemagick]: imagemagick.md