Image Manipulation Image Magick

Image Manipulation with ImageMagick

This skill enables image processing and manipulation tasks using ImageMagick across Windows, Linux, and macOS systems.

When to Use This Skill

Use this skill when you need to:

• Resize images (single or batch)
• Get image dimensions and metadata
• Convert between image formats
• Create thumbnails
• Process wallpapers for different screen sizes
• Batch process multiple images with specific criteria

Prerequisites

• ImageMagick installed on the system
• Windows: PowerShell with ImageMagick available as magick (or at C:\Program Files\ImageMagick-*\magick.exe)
• Linux/macOS: Bash with ImageMagick installed via package manager (apt, brew, etc.)

Core Capabilities

1. Image Information

• Get image dimensions (width x height)
• Retrieve detailed metadata (format, color space, etc.)
• Identify image format

2. Image Resizing

• Resize single images
• Batch resize multiple images
• Create thumbnails with specific dimensions
• Maintain aspect ratios

3. Batch Processing

• Process images based on dimensions
• Filter and process specific file types
• Apply transformations to multiple files

Operating Workflow

1. Resolve magick before using it
   • PowerShell: store the executable in $magick and invoke with & $magick
   • Bash: require command -v magick before processing
2. Inspect first: use magick identify -format "%wx%h" "path/to/image.jpg" for dimensions or magick identify -verbose "path/to/image.jpg" for full metadata
3. Transform with quoted paths and explicit outputs:
   • Resize: magick "input.jpg" -resize 427x240 "output.jpg"
   • Thumbnail: magick "$img" -resize 427x240 "thumbnails/thumb_$filename"
   • Exact resize only when intended: -resize 427x240!
   • Minimum-fill resize only when intended: -resize 427x240^
4. Batch with platform-native loops:
   • PowerShell: Get-ChildItem "path/to/images/*" | ForEach-Object { ... }
   • Bash: for img in path/to/images/*; do ...; done
5. Filter by dimensions when processing only matching source images:
   • PowerShell: $dimensions = & $magick identify -format "%w,%h" $_.FullName
   • Bash: dimensions=$(magick identify -format "%w,%h" "$img")

Detailed command examples and reusable snippets live in references/command-examples.md.

Required follow-up reads

Safety Constraints

1. Always quote file paths that may contain spaces
2. Do not overwrite originals by accident: write to an output directory or distinct filename unless the user explicitly requests in-place edits
3. Use PowerShell call syntax: invoke a stored executable path with & $magick
4. Verify dimensions before expensive or conditional batch work to avoid unnecessary processing
5. Choose resize semantics deliberately: plain WxH preserves aspect ratio within the box, WxH! distorts to exact dimensions, and WxH^ fills at least the target dimensions
6. Expect memory pressure on large batches; process files iteratively and avoid loading unrelated images

Validation Guidance

• Confirm ImageMagick is available before generating commands
• Run identify on representative input before and after transformations when dimensions, format, color space, or metadata matter
• For batch commands, validate on one file first, then apply the same command shape in the loop
• Check output files exist and dimensions match the requested behavior
• On older Linux systems with ImageMagick 6.x, convert may be needed instead of magick; prefer magick when available

Limitations

• Large batch operations may be memory-intensive
• Some complex operations may require additional ImageMagick delegates
• On older Linux systems, use convert instead of magick (ImageMagick 6.x vs 7.x)