mogrify

Perform operations on multiple images, such as resizing, cropping, flipping, and adding effects. Changes are applied directly to the original file. Part of ImageMagick. More information: https://imagemagick.org/script/mogrify.php.

mogrify -resize 50% *.jpg

mogrify -resize 800x600 DSC*

mogrify -format jpg *.png

mogrify -modulate 100,50 *

mogrify -modulate 200 *