imagemagick

Image modification

Downscale

magick mogrify -auto-orient -strip -resize "1920x1920>" -quality 85 *.jpg

Remove first pixel row

magick convert input.png -chop 0x1 output.png

Convert to webp

magick convert -auto-orient -strip -resize "600x600>" -quality 75 -define webp:method=6 -define webp:use-sharp-yuv=1 image.jpg image.webp

Batch processing

for i in *.jpg; do magick convert /* your options */ $i ${i/.jpg/.webp}; done

Preserve timestamp

magick mogrify -define preserve-timestamp=true <filename.jpg>

Iterate big files

find . \( -iname "*.jpg" -o -iname "*.jpeg" \) -type f -size +1500k -exec magick mogrify [...] {} \;

Crop from center

magick convert -gravity Center -crop 240x240+0+0 input.jpg output.jpg

Image information

Quality of jpeg

magick identify -format '%Q' <filename.jpg>

Exif tags and general info

magick identify -verbose input.jpg

Signature hash of image (pixels only, metadata is ignored, see links below)

magick identify -format %# input.jpg

Animation

Create gif

magick convert -delay 30 -loop 0 -resize 50% *.jpg animation.gif

Color reduction

Reduce colors

magick convert input.png +dither -colors 16 output.png

Posterize

magick convert input.png -posterize 8 output.png

Diff image

Show differences in red

magick compare image1.png image2.png -compose src diff.png

Subtract image

magick composite image1.png image2.png -compose difference diff.png

PDF

Convert images to pdf

magick convert *.jpg -auto-orient -background white -units pixelsperinch -density 72 -page a4 output.pdf

Favicon

Convert .svg to .ico

magick -density 256x256 -background transparent favicon.svg -define icon:auto-resize -colors 256 favicon.ico

Specify sizes

-define icon:auto-resize=16,24,32,64

Convert .svg to .png

magick -density 128x128 -background transparent favicon.svg -resize 192x192 favicon.png

Check generated .ico file

icotool --list favicon.ico

Reduce size of svg or png

optipng

optipng image.png

pngquant (lossy)

pngquant image.png

svgo

svgo image.svg -o image.min.svg

See here: https://imagemagick.org/script/command-line-options.php#format_identify_

and here: https://imagemagick.org/script/escape.php