ImageMagick is a free and open-source software suite for image editing. It is my go-to command-line tool for converting, modifying, and editing images.
While your Adobe Creative Cloud Suite might be capable of doing all the same things, ImageMagick has all the benefits of a command-line tool, namely better reproducibility, and efficiency when converting lots of images. Did I mention that imagemagick is free?
Another advantage is ImageMagick’s unparalleled ability to read more than 100 image file formats and easily convert one into the other.
Below, I keep a running list of all commands I ever needed, so I don’t have to google them again.
Modifying single files
Reduce the quality of a jpg
convert big_image.jpg -strip -quality 90 small_image.jpg
Compress a pdf, resize it, and increase the contrast by stretching the range of intensity values
convert big_pdf.pdf -contrast-stretch 1x1% -resize 20% -compress Group4 small_pdf.pdf
Crop a single image to a specific format. The format is -crop x_size x y_size + x_offset + y_offset.
convert input.png -crop 1900x1800+300+100 output.png
Processing multiple files
Crop multiple files. The format is -crop x_size x y_size + x_offset + y_offset.
mkdir cropped mogrify -crop 1800x1700+300+100 -path ./cropped *.png
Convert all files in a directory to the same width and reformat to jpg
mkdir output mogrify -path ./output -resize 180 -format jpg *.*
Convert all jpgs in a directory to same size, reduce their quality, and output as jpg.
mkdir output mogrify -path ./output -resize 900 -quality 80 -format jpg *.jpg
Reduce the quality of all jpgs in a directory
mogrify -quality 80% *.jpg