ImageMagick is a free and open-source set of tools for displaying, converting, editing raster image (grid of pixels, resolution dependent) and vector image (mathematical curves and shapes, resolution independent) files. It’s a Swiss army knife of image manipulation and editing via command-line interface.

📝 IM is an extremely advanced tool with numerous functions and features. This blog will be updated based on my usage and familiarity of IM over time.

Conversion between Image Formats

You can easily convert between image formats

magick image.png image.jpg

It will convert the .png image to .jpg format.

OR

magick image.png image.webp

It will convert the .png to .webp image format, suitable for Web usage.

The .WEBP images are standard on the web, due to their small size and lazy loading features. To get instant loading of images on the web, you can use -quality attribute to further reduce the size of .webp images without significant quality degradation.

magick -quality 70 image.png image.webp

To batch convert multiple .PNGs in the current working directory:

for img in *.png; do magick "$img" -quality 70 "${img%.png}.webp"; done

Before running the scriptlet, you can see with echo command, what will happen when the scriptlet is run:

for img in *.png
do 
echo magick "$img" -quality 70 "${img%.png}.webp"
done

• for img in *.png Loop through each PNG file in the current directory, store the filename in a variable called img
• do Start of the loop
• "$img" Holds the current filename during each loop iteration, the double quotes "" makes sure, space and other characters in the filenames are handled correctly.
• "${img%.png}.webp" It replaces the .png in the filename.png with .webp, the operator % removes from the right (in our case replaces image extension names).
• done Ends the loop and repeats for the next PNG file.
• The semicolon ; acts as a command terminator, ; also separates the loop declaration from the do, it’s a syntax requirement when do is written immediately after. New line can act as a command terminator too, when not writing the scriptlet on a single line.
• Test scriptlet is written without semicolons as new lines are acting as command terminator.

Combine Images

You can combine two images either horizontally or vertically, by using.

magick image1.png image2.png -append combined.png

Image1 and Image2 will be combined vertically, first on the top and second in the bottom. To combine them horizontally replace -append with +append.

The short form:

magick image{1,2}.png -append combined.png

You can use image{1..4}.png, which expands to image1, image2, image3 and image4.

Before running above command, you can add echo in the start to see how braces will be expanded without executing it.

echo magick image{1,2}.png -append combined.png

Resize an Image

To resize an image:

magick input_image -resize WIDTHxHEIGHT output_image

You can just use WIDTHx, the height will be adjusted accordingly.

You can also use percentage as a parameter:

magick input_image -resize 70% output_image

It will resize the image to 70% of its original size.

Compress an Image

To compress a JPEG/JPG image:

magick input.jpg -define jpeg:extent=[SIZE] compressed.jpg

• The =[size] could be in bytes, bits, kb, KB, KiB etc.
• The size would not be exactly as the given value. It could vary a bit lower or higher from the defined value.
• The specific :exten=[SIZE] is only available for JPEG/JPG image format.

Example usage:

magick input.jpg -define jpeg:extent=2MiB compressed.jpg

To compress a WebP, we need to manually adjust the -quality from 0 to 100 where is no compression, and 100 is the highest compression possible.

magick input.webp -quality 75 output.webp

• It will compress the WebP by 75%.

📝 INFO

Standard PNG is a lossless format, which do support -quality flag with values from 0 to 9, due to the nature of compression, you may even get higher sized PNGs after compression. The best mode of action is to convert your PNG into JPEG/WebP first, if you need to compress it using IM.

Create a GIF

Create a .gif from all the PNGs in the current directory:

magick *.png output.gif

With -loop, you can set how many times, the GIF should loop through before stopping.

magick *.png -loop 5 output.gif

You can set -delay for animation too.

Rotate an Image

To rotate an image:

magick input_image -rotate 90 output_image

It will rotate the image clockwise by 90 degrees.

To rotate counterclockwise by 90 degrees:

magick input_image -rotate -90 output_image

Add a Border to an Image

To set a border around an image:

magick input_image -bordercolor COLORNAME -border WIDTHxHEIGHT output_image

To add a border of 5 pixels around the edge of an image, with border color purple:

magick input_image -bordercolor purple -border 5x5 output_image

Grayscale Effect on an Image

To add a grayscale effect to an image:

magick input_image -colorspace gray output_image

Strip EXIF Data from an Image

To strip all EXIT/metadata from an image:

magick input_image -strip output_private_image

This operation will remove all the EXIF data, and also reduces the size of an image significantly.

References

• Examples of ImageMagick Usage — The In-depth Official Documentation
• ImageMagick — Tips & Tricks from ArchWiki
• Fred’s ImageMagick Scripts — Useful ImageMagick Scripts
• Unlock the Power of ImageMagick — (An old IM Version Beginner)
• ImageMagick Guide — (Adopt the Command for Newer IM Version)