https://askubuntu.com/questions/1164/how-to-easily-resize-images-via-command-line



sudo apt install imagemagick;
sudo apt install graphicsmagick-imagemagick-compat;



sudo apt install imagemagick-6.q16;
sudo apt install imagemagick-6.q16hdri;


# - Working command - #
mogrify -resize 320x240 *.jpg *.png *.jpeg



mogrify -verbose -resize '40%' *.JPG



convert -resize 1024X768  source.png dest.jpg
convert -resize 50% myfigure.png myfigure.jpg
convert myfigure.png -resize 200x100 myfigure.jpg

mogrify -resize 50% *.png      # keep image aspect ratio
mogrify -resize 320x240 *.png  # keep image aspect ratio
mogrify -resize 320x240! *.png # don't keep image aspect ratio
mogrify -resize x240 *.png     # don't keep image aspect ratio
mogrify -resize 320x *.png     # don't keep image aspect ratio
convert -resize 1024X768  source.png dest.jpg

mogrify -quality 10% carlo*.png
mogrify -quality 10% uno*.jpg