ImageMagick Field Guide

Table of Contents

• Resize an Image for the Web
• Reduce Animated GIF File Size
• Combine Multiple Images into an Animated GIF
• Stack Images Vertically
• ImageMagick with a URL
• Conventions Used in This Guide

Resize an Image for the Web

magick input.png \
    -resize 800x> \
    -strip \
    -quality 75 \
    -interlace Plane \
    output.jpg

-resize 800x>

Set the width to 800px and maintain aspect ratio without upscaling smaller images. Use 800x to also upscale smaller images.

-strip

Remove EXIF, IPTC, XMP, and embedded color profiles to reduce file size.

-quality 75

Set JPEG compression to 75.

-interlace Plane

Interlace the image so that it progressively sharpens as more data arrives.

Reduce Animated GIF File Size

magick input.gif \
    -fuzz 7% \
    -layers optimize \
    output.gif

fuzz 7%

Allow a 7% color difference when comparing pixels for optimization. This helps further reduce size by treating near-identical colors as the same.

-layers optimize

Optimize the GIF animation by reducing redundant pixels between frames, which can reduce file size.

Combine Multiple Images into an Animated GIF

magick input1.png input2.png input3.png \
    -delay 100 \
    -loop 5 \
    -dispose previous \
    output.gif

-delay 100

Pause for 1 second between frames.

-loop 5

Loop the frames five times. Use -loop 0 to loop forever.

-dispose previous

Clears the previous frame before drawing the next.

Stack Images Vertically

magick input1.jpg input2.jpg input3.jpg \
    -append \
    result.jpg

-append

Stack images vertically. Use +append to stack horizontally instead.

ImageMagick With a URL

magick https://example.com/input.png \
    result.jpg

Requires ImageMagick compiled with HTTPS delegate support. Some ImageMagick builds disable remote reading.

Conventions Used in This Guide

• Use input.png and output.jpg as the filenames (extensions can change as needed).
• Put one switch on each line.
• Use future tense such as "optimize" instead of "optimizes" or "optimized".
• Use AP style heading capitalization.
• Use the newer magick command instead of the older convert command.
• Arbitrarily organize into what I think are the most likely use cases.

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