ImageMagick Skill

ImageMagick is a powerful command-line tool for reading, converting, resizing, rotating, and manipulating images. It supports over 100 image formats and provides extensive image processing capabilities.

When to Use

Use ImageMagick when you need to:

• Convert images between formats (JPEG, PNG, WebP, AVIF, etc.)
• Resize images (thumbnails, responsive images, optimization)
• Rotate or flip images
• Apply filters and effects (blur, sharpen, adjust colors, etc.)
• Batch process multiple images
• Create image composites or combine images
• Extract image metadata or information
• Optimize images for web (compression, format conversion)
• Generate image variants (different sizes, formats)

Core Commands

Basic Conversion

magick input.jpg output.png                    # Convert format
magick input.png output.webp                   # Convert to WebP
magick input.jpg -resize 50% output.jpg        # Resize to 50%
magick input.jpg -rotate 90 output.jpg        # Rotate 90 degrees

Reading Image Information

magick identify image.jpg                      # Get image info
magick identify -format "%wx%h" image.jpg     # Get dimensions
magick identify -format "%[size]" image.jpg    # Get file size

Common Operations

Resize

• magick input.jpg -resize 800x600 output.jpg – Resize to exact dimensions
• magick input.jpg -resize 50% output.jpg – Resize by percentage
• magick input.jpg -resize 800x600^ output.jpg – Resize to fit (maintain aspect)
• magick input.jpg -resize 800x600\> output.jpg – Only resize if larger
• magick input.jpg -thumbnail 200x200 output.jpg – Create thumbnail

Rotate

• magick input.jpg -rotate 90 output.jpg – Rotate 90° clockwise
• magick input.jpg -rotate -90 output.jpg – Rotate 90° counter-clockwise
• magick input.jpg -rotate 45 output.jpg – Rotate 45°
• magick input.jpg -flip output.jpg – Flip vertically
• magick input.jpg -flop output.jpg – Flip horizontally

Format Conversion

• magick input.jpg output.png – JPEG to PNG
• magick input.png output.webp – PNG to WebP
• magick input.jpg output.avif – JPEG to AVIF
• magick input.png -quality 85 output.jpg – PNG to JPEG with quality

Quality & Compression

• magick input.jpg -quality 85 output.jpg – Set JPEG quality (1-100)
• magick input.png -quality 90 output.webp – Set WebP quality
• magick input.jpg -strip output.jpg – Remove metadata (reduce size)
• magick input.jpg -sampling-factor 4:2:0 output.jpg – Optimize JPEG

Filters & Effects

• magick input.jpg -blur 0x2 output.jpg – Apply blur
• magick input.jpg -sharpen 0x1 output.jpg – Sharpen image
• magick input.jpg -brightness-contrast 10x5 output.jpg – Adjust brightness/contrast
• magick input.jpg -modulate 100,150,100 output.jpg – Adjust brightness, saturation, hue
• magick input.jpg -grayscale output.jpg – Convert to grayscale
• magick input.jpg -sepia-tone 80% output.jpg – Apply sepia effect

Cropping

• magick input.jpg -crop 800x600+100+50 output.jpg – Crop (width x height + x + y)
• magick input.jpg -crop 50%x50%+25%+25% output.jpg – Crop by percentage
• magick input.jpg -gravity center -crop 800x600+0+0 output.jpg – Center crop

Batch Processing

• magick *.jpg -resize 50% resized_%d.jpg – Resize all JPGs
• magick *.png -quality 85 converted_%d.jpg – Convert all PNGs to JPEG
• magick input*.jpg -append output.jpg – Append images vertically
• magick input*.jpg +append output.jpg – Append images horizontally

Common Use Cases

Web Optimization

# Convert to WebP with quality optimization
magick input.jpg -quality 85 -strip output.webp

# Create responsive image sizes
magick input.jpg -resize 1920x1080\> large.jpg
magick input.jpg -resize 1280x720\> medium.jpg
magick input.jpg -resize 640x360\> small.jpg

# Generate thumbnail
magick input.jpg -thumbnail 200x200 -strip thumb.jpg

Format Conversion

# JPEG to PNG (preserve transparency)
magick input.jpg output.png

# PNG to JPEG (with white background)
magick input.png -background white -flatten output.jpg

# Convert to AVIF (modern format)
magick input.jpg -quality 90 output.avif

Image Manipulation

# Rotate and resize
magick input.jpg -rotate 90 -resize 50% output.jpg

# Apply multiple effects
magick input.jpg -brightness-contrast 10x5 -sharpen 0x1 output.jpg

# Create composite
magick background.jpg logo.png -gravity center -composite output.jpg

Best Practices

1. Use magick command – Modern ImageMagick uses magick (not convert)
2. Preserve aspect ratio – Use \> or ^ modifiers when resizing
3. Strip metadata – Use -strip for web images to reduce file size
4. Quality settings – Use 80-90 for JPEG, 85-95 for WebP
5. Batch operations – Use wildcards and %d for sequential numbering
6. Check before processing – Use identify to verify image properties
7. Optimize for web – Combine -strip, -quality, and format conversion

Command Aliases

• magick – Modern command (recommended)
• convert – Legacy alias (still works)
• identify – Get image information
• mogrify – In-place image modification

Installation

ImageMagick is already installed. If needed:

# macOS
brew install imagemagick

# Linux
sudo apt-get install imagemagick  # Debian/Ubuntu
sudo yum install ImageMagick      # RHEL/CentOS

# Verify installation
magick --version

References

• Official Documentation: https://imagemagick.org/script/convert.php
• Command-line Options: https://imagemagick.org/script/command-line-options.php
• Examples: https://imagemagick.org/script/examples.php