image-processing - SKILL.md Agent Skill

name: image-processing description: > Process images using ImageMagick for format conversion, resizing, cropping, batch processing, effects, composition, watermarks, and optimization. This skill should be used when the user wants to convert image formats (PNG, JPEG, WebP, GIF), resize or crop images, apply effects (blur, sharpen, sepia, grayscale), add watermarks or text overlays, batch process multiple images, create thumbnails, or optimize images for web.

Image Processing Skill

Process images using ImageMagick command-line tools for conversion, optimization, and manipulation tasks.

Installation

macOS

brew install imagemagick

Ubuntu/Debian

sudo apt-get install imagemagick

Windows

winget install ImageMagick.ImageMagick
# Or download: https://imagemagick.org/script/download.php

Verify Installation

magick -version
# or
convert -version

Quick Start Examples

Image Processing

# Convert format
magick input.png output.jpg

# Resize maintaining aspect ratio
magick input.jpg -resize 800x600 output.jpg

# Create square thumbnail
magick input.jpg -resize 200x200^ -gravity center -extent 200x200 thumb.jpg

Batch Image Resize

# Resize all JPEGs to 800px width
mogrify -resize 800x -quality 85 *.jpg

# Output to separate directory
mogrify -path ./output -resize 800x600 *.jpg

Image Watermark

# Add watermark to corner
magick input.jpg watermark.png -gravity southeast \
  -geometry +10+10 -composite output.jpg

Common Workflows

Create Responsive Images

# Generate multiple sizes
for size in 320 640 1024 1920; do
  magick input.jpg -resize ${size}x -quality 85 "output-${size}w.jpg"
done

Batch Image Optimization

# Convert PNG to optimized JPEG
mogrify -path ./optimized -format jpg -quality 85 -strip *.png

Image Blur Effect

# Gaussian blur
magick input.jpg -gaussian-blur 0x8 output.jpg

Advanced Techniques

Complex Image Pipeline

# Resize, crop, border, adjust
magick input.jpg \
  -resize 1000x1000^ \
  -gravity center \
  -crop 1000x1000+0+0 +repage \
  -bordercolor black -border 5x5 \
  -brightness-contrast 5x10 \
  -quality 90 \
  output.jpg

Animated GIF from Images

# Create with delay
magick -delay 100 -loop 0 frame*.png animated.gif

# Optimize size
magick animated.gif -fuzz 5% -layers Optimize optimized.gif

Media Analysis

Image Information

# Basic info
identify image.jpg

# Detailed format
identify -verbose image.jpg

# Custom format
identify -format "%f: %wx%h %b\n" image.jpg

Performance Tips

Batch with mogrify - In-place image processing
Strip metadata - Reduce file size with -strip
Progressive JPEG - Better web loading with -interlace Plane
Limit memory - Prevent crashes on large batches
Test on samples - Verify settings before batch
Parallel processing - Use GNU Parallel for multiple files

Reference Documentation

Detailed guides in references/:

imagemagick-editing.md - Format conversion, effects, transformations
imagemagick-batch.md - Batch processing, mogrify, parallel operations

Common Parameters

ImageMagick Geometry

800x600 - Fit within (maintains aspect)
800x600! - Force exact size
800x600^ - Fill (may crop)
800x - Width only
x600 - Height only
50% - Scale percentage

Troubleshooting

ImageMagick "not authorized"

# Edit policy file
sudo nano /etc/ImageMagick-7/policy.xml
# Change <policy domain="coder" rights="none" pattern="PDF" />
# to <policy domain="coder" rights="read|write" pattern="PDF" />

Memory errors

# Limit memory usage
magick -limit memory 2GB -limit map 4GB input.jpg output.jpg

Resources

ImageMagick: https://imagemagick.org/
ImageMagick Usage: https://imagemagick.org/Usage/