• https://en.wikipedia.org/wiki/ImageMagick
• http://www.imagemagick.org/script/index.php
• https://en.wikipedia.org/wiki/GraphicsMagick
• http://www.graphicsmagick.org/

for i in *.jpg; do
    convert -strip -interlace Plane -gaussian-blur 0.05 -quality 75% -resize 1800x $i output/$i
done