using imagemagick commands to resixe and compres a folder full of photos:
imagemagick install: used get-apt.
sudo apt-get install imagemagick
see website for commands, but basic ones:
convert -resize 750 *.JPG
convert -quality 80% *.jpg
or together:
convert -resize 750 -quality 80% *.JPG
the JPG is case sensitive; the size sets the width at this and the height proportional to it;