imagemagick-conversion

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Convert and manipulate images with ImageMagick. Covers format conversion, resizing, batch processing, quality adjustment, and image transformations. Use when user mentions image conversion, resizing images, ImageMagick, magick command, batch image processing, or thumbnail generation.

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Sourcelaurigates/claude-plugins
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NPX Install

npx skill4agent add laurigates/claude-plugins imagemagick-conversion

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imagemagickimage-processingcommand-line-toolbatch-processingimage-conversion

SKILL.md Content

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ImageMagick Image Conversion

Project: Project-independent Gitignored: Yes

Trigger

Use this skill when users request image manipulation tasks including:
  • Converting between image formats (PNG, JPEG, WebP, GIF, TIFF, etc.)
  • Resizing images (dimensions, percentages, aspect ratios)
  • Batch processing multiple images
  • Adjusting image quality and compression
  • Creating thumbnails
  • Basic image transformations (rotate, flip, crop)

Overview

ImageMagick is a powerful command-line tool for image processing. This skill provides guidance for using the 
magick
command to perform common image conversion and manipulation tasks.
Key Command Pattern:
bash
magick input-file [options] output-file

Common Use Cases

Format Conversion

Basic format conversion:
bash
magick image.jpg image.png
magick photo.png photo.webp
Batch convert all JPEGs to PNG:
bash
magick mogrify -format png *.jpg
Convert with specific output directory:
bash
mkdir -p output
magick mogrify -format webp -path output/ *.jpg

Resizing Images

Resize by percentage:
bash
magick image.jpg -resize 50% output.jpg
Resize to specific width (maintain aspect ratio):
bash
magick image.jpg -resize 800x output.jpg
Resize to specific height (maintain aspect ratio):
bash
magick image.jpg -resize x600 output.jpg
Resize to fit within dimensions (maintain aspect ratio):
bash
magick image.jpg -resize 800x600 output.jpg
Resize to exact dimensions (ignore aspect ratio):
bash
magick image.jpg -resize 800x600! output.jpg
Resize only if larger:
bash
magick image.jpg -resize '800x600>' output.jpg
Resize only if smaller:
bash
magick image.jpg -resize '800x600<' output.jpg

Quality and Compression

Set JPEG quality (1-100, default 92):
bash
magick image.jpg -quality 85 output.jpg
Optimize PNG compression:
bash
magick image.png -quality 95 output.png
Create high-quality WebP:
bash
magick image.jpg -quality 90 output.webp

Thumbnails

Generate thumbnail (fast, lower quality):
bash
magick image.jpg -thumbnail 200x200 thumb.jpg
Generate thumbnail with padding:
bash
magick image.jpg -thumbnail 200x200 -background white -gravity center -extent 200x200 thumb.jpg

Batch Operations

Resize all images in directory:
bash
magick mogrify -resize 800x600 -path resized/ *.jpg
Convert and resize in one operation:
bash
magick mogrify -resize 1200x -format webp -quality 85 -path output/ *.jpg
Process specific file types:
bash
magick mogrify -resize 50% -path smaller/ *.{jpg,png,gif}

Image Information

Display image information:
bash
magick identify image.jpg
Detailed image information:
bash
magick identify -verbose image.jpg

Advanced Transformations

Rotate image:
bash
magick image.jpg -rotate 90 rotated.jpg
Flip horizontally:
bash
magick image.jpg -flop flipped.jpg
Flip vertically:
bash
magick image.jpg -flip flipped.jpg
Crop to specific region:
bash
magick image.jpg -crop 800x600+100+100 cropped.jpg
Auto-orient based on EXIF:
bash
magick image.jpg -auto-orient output.jpg
Strip metadata (reduce file size):
bash
magick image.jpg -strip output.jpg

Important Notes

mogrify vs convert

  • magick mogrify
    : Modifies files in-place or writes to specified path
    • Use 
      -path
      option to preserve originals
    • Efficient for batch operations
  • magick convert
     (or just 
    magick
    ): Creates new files
    • Always preserves original
    • Better for single-file operations

Performance Tips

  1. Use 
    -thumbnail
    for thumbnails    : Faster than 
    -resize
    for small previews
  2. Use 
    -strip
    to remove metadata    : Reduces file size significantly
  3. Batch operations: Process multiple files in one 
    mogrify
    command
  4. Quality settings: 85-90 is usually optimal for JPEG (balances size/quality)

Format Recommendations

  • JPEG: Photos, complex images with gradients (lossy)
  • PNG: Screenshots, graphics with transparency (lossless)
  • WebP: Modern format, excellent compression (lossy or lossless)
  • GIF: Simple animations, limited colors
  • TIFF: Archival, high-quality storage

Safety Considerations

Always test commands on copies first:
bash
# Create test directory
mkdir -p test-output

# Test on single file
magick original.jpg -resize 50% test-output/test.jpg

# Verify result before batch processing
Use 
-path
with mogrify to preserve originals:
bash
# This preserves originals in current directory
magick mogrify -resize 800x -path resized/ *.jpg
Quote wildcards in shell:
bash
# Prevents premature shell expansion
magick mogrify -resize '800x600>' -path output/ '*.jpg'

Common Patterns

Web Optimization Workflow

bash
# Create optimized versions for web
mkdir -p web-optimized

# Convert to WebP with quality 85, resize to max 1920px width
magick mogrify -resize 1920x -quality 85 -format webp -path web-optimized/ *.jpg

# Strip metadata to reduce size
magick mogrify -strip web-optimized/*.webp

Thumbnail Generation

bash
# Create thumbnail directory
mkdir -p thumbnails

# Generate 300x300 thumbnails with white padding
for img in *.jpg; do
  magick "$img" -thumbnail 300x300 -background white -gravity center -extent 300x300 "thumbnails/${img%.jpg}_thumb.jpg"
done

Multi-Format Export

bash
# Export to multiple formats for compatibility
mkdir -p exports/{png,webp,jpg}

for img in source/*.png; do
  name=$(basename "$img" .png)
  magick "$img" -quality 90 "exports/png/$name.png"
  magick "$img" -quality 85 "exports/webp/$name.webp"
  magick "$img" -quality 85 "exports/jpg/$name.jpg"
done

Troubleshooting

Check ImageMagick version:
bash
magick -version
Verify supported formats:
bash
magick identify -list format
Test command on single file first:
bash
# Always test before batch operations
magick test-image.jpg -resize 50% test-output.jpg

When to Use This Skill

✓ Use this skill for:
  • Format conversions between standard image types
  • Resizing operations (dimensions, percentages)
  • Quality adjustments and compression
  • Batch processing workflows
  • Generating thumbnails or previews
  • Basic transformations (rotate, crop, flip)
✗ Don't use this skill for:
  • Advanced photo editing (use GIMP, Photoshop)
  • Complex filters or effects (consider dedicated tools)
  • Video processing (use FFmpeg)
  • Vector graphics (use Inkscape, Illustrator)

Integration with Workflows

This skill complements other development workflows:
  • Web development: Optimize images for deployment
  • Documentation: Generate screenshots and diagrams
  • CI/CD: Automate image processing in pipelines
  • Content creation: Prepare images for various platforms
The 
magick
command is typically available via Homebrew (
brew install imagemagick
) or system package managers.