Convert to kindle screensaver

kindle_screensavers

for i in *jpg; do
  name=$(echo $i |awk -F_ '{print $4}' |sed 's/\.jpg$//')
  convert -size 600x800 xc:white \
      $i -type Grayscale -resize 600x800 -gravity center -extent 600x800^ \
      ~/Downloads/Kindle\ Stamp/stamp.png -flatten kindle/$name.jpg
done