Commmonly used imagemagick commands.

ImageMagick is an open source tool for editing and converting raster images created in 1987 by John Cristy.

I use ImageMagick on the command line for quick image edits such as cropping, resizing or rotating. It is also used in the batchVariants script that prepares the images for this website.

Use convert to create a new output file or mogrify to overwrite the input file.


mogrify -format jpg *.pdf

Converts all pdf files at location from pdf to jpg.


mogrify -rotate "90" file.jpg

Rotates an image by 90 degrees clockwise.


convert -crop 640x480+50+100 +repage input.jpg output.jpg

Crops the image at X:50 Y:100 to a size of W: 640 H:480.
+repage will prevent export of the cropped area.

convert -crop 3:2+50+100 +repage input.jpg output.jpg

Crops the image at X:50 Y:100 to a ratio of W: 3 H:2

convert -crop 3:2+50+100 +repage input.jpg output.jpg

Crops the image at X:50 Y:100 to a ratio of W: 3 H:2


mogrify -geometry 50% file.jpg

Resizes the image down by half.

mogrify -geometry 1024x file.jpg

Resizes the image to a width of 1024px.

mogrify -geometry x800 file.jpg

Resizes the image to a height of 800px.

mogrify -geometry 800x800 file.jpg

Resizes the image to 800px at the longer side.

mogrify -density 72 -units pixelsperinch file.jpg

Changes the DPI of the image to 72.


convert input.png -colorspace RGB -background "rgb(255,255,255)" -flatten output.png

Adds a background color to a transparent png

convert input.png -gravity center -background white -extent 200x200  output.jpg

Extens the canvas of an image to specified size.

convert input.png -channel RGB -negate output.png

Inverts the colors of an image.


convert input.jpg -dither FloydSteinberg -colors 8 output.jpg

Dithers the image with 8 colors.


montage * output.jpg

Tiles all images in folder.

montage * output.jpg -background "#000000"

Sets the background color the black.

PDF conversion

convert file.pdf -flatten output.jpg

Converts a pdf to.jpg

convert -density 300 input.pdf -brightness-contrast -20x20 -sharpen 0x1 output.pdf

Adjusts brightness, contrast and sharpness of a scanned pdf document.

Image Sequencing

convert -delay 200 -loop 0 *.jpg output.gif

Creates an infinitely looping GIF with 2 seconds delay between each frame.


identify file.jpg

Displays information on the file such as width and height.

Offline Documentation

To make the documentation available offline, install the imagemagick-6-doc package.


convert in.jpg -colorspace gray out.jpg

Converts an image to grayscale.

Cache Policy

In case a process exhausts the cache resources, find /etc/ImageMagick-6/policy.xml and increase the value property in this line:

<policy domain="resource" name="disk" value="1GiB"/>

Security Policy blocking conversion

In case conversion is blocked because of a security policy workaround for an older version of Ghostscript, comment out the whole block in /etc/ImageMagick-6/policy.xml

 <policy domain="coder" rights="none" pattern="PS" />
 <policy domain="coder" rights="none" pattern="PS2" />
 <policy domain="coder" rights="none" pattern="PS3" />
 <policy domain="coder" rights="none" pattern="EPS" />
 <policy domain="coder" rights="none" pattern="PDF" />
 <policy domain="coder" rights="none" pattern="XPS" />


incoming(4) | memoir | scim | meta | software