imagemagick

CLI

Create, edit, and convert images from the command line.

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Installation

Homebrewbrew install imagemagick

ImageMagick

Batch convert, resize, and manipulate images

When to use

Image format conversion, resizing, or batch processing

Examples

Convert PDF to image🟢 94% success

convert -density 150 input.pdf output.png

⚠ Common failures (2)

Blurry/low resolution output → -density option is required; use -density 150 or higher before the input file
Policy error: not authorized → Edit /etc/ImageMagick-6/policy.xml and change PDF rights from 'none' to 'read|write'

Fallback:pdftoppm -r 150 input.pdf output

Resize image to percentage🟢 99% success

convert input.jpg -resize 50% output.jpg

Resize image to exact dimensions🟢 98% success

convert input.jpg -resize 800x600! output.jpg

⚠ Common failures (1)

Aspect ratio changed unexpectedly → Use 800x600 without ! to keep aspect ratio, or 800x to fix only width

Batch convert PNG to JPEG🟢 91% success

convert '*.png' -quality 85 'output_%d.jpg'

⚠ Common failures (1)

Only one file converted → Use mogrify instead: mogrify -format jpg -quality 85 *.png

Fallback:mogrify -format jpg -quality 85 *.png