mogrify

Perform operations on multiple images, such as resizing, cropping, flipping, and adding effects. Changes are applied directly to the original file.

Resize all JPEG images in the folder to 50% of their initial size:

mogrify -resize {{50%}} {{*.jpg}}

Resize all images starting with "DSC" to 800x600:

mogrify -resize {{800x600}} {{DSC*}}

Convert all PNG images in the folder to JPEG:

mogrify -format {{jpg}} {{*.png}}

Halve the saturation of all image files in the current directory:

mogrify -modulate {{100,50}} {{*}}

Double the brightness of all image files in the current directory:

mogrify -modulate {{200}} {{*}}