Image Manipulation with ImageMagick

This skill enables image processing and manipulation tasks using ImageMagick on Windows 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
• PowerShell environment (Windows)
• ImageMagick executable available as magick (recommended), or at a known path (commonly under C:\Program Files\ImageMagick-*\magick.exe).

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

Usage Examples

Example 0: Resolve magick executable (recommended)

# Prefer ImageMagick on PATH
$magick = (Get-Command magick -ErrorAction SilentlyContinue)?.Source

# Fallback: common install pattern under Program Files
if (-not $magick) {
    $magick = Get-ChildItem "C:\\Program Files\\ImageMagick-*\\magick.exe" -ErrorAction SilentlyContinue |
        Select-Object -First 1 -ExpandProperty FullName
}

if (-not $magick) {
    throw "ImageMagick not found. Install it and/or add 'magick' to PATH."
}

Example 1: Get Image Dimensions

# For a single image
& $magick identify -format "%wx%h" path/to/image.jpg

# For multiple images
Get-ChildItem "path/to/images/*" | ForEach-Object { 
    $dimensions = & $magick identify -format "%f: %wx%h`n" $_.FullName
    Write-Host $dimensions 
}

Example 2: Resize Images

# Resize a single image
& $magick input.jpg -resize 427x240 output.jpg

# Batch resize images
Get-ChildItem "path/to/images/*" | ForEach-Object { 
    & $magick $_.FullName -resize 427x240 "path/to/output/thumb_$($_.Name)"
}

Example 3: Get Detailed Image Information

# Get verbose information about an image
& $magick identify -verbose path/to/image.jpg

Example 4: Process Images Based on Dimensions

Get-ChildItem "path/to/images/*" | ForEach-Object { 
    $dimensions = & $magick identify -format "%w,%h" $_.FullName
    if ($dimensions) {
        $width,$height = $dimensions -split ','
        if ([int]$width -eq 2560 -or [int]$height -eq 1440) {
            Write-Host "Processing $($_.Name)"
            & $magick $_.FullName -resize 427x240 "path/to/output/thumb_$($_.Name)"
        }
    }
}

Guidelines

1. Always quote file paths - Use quotes around file paths that might contain spaces
2. Use the & operator - Invoke the magick executable using & in PowerShell
3. Store the path in a variable - Assign the ImageMagick path to $magick for cleaner code
4. Wrap in script blocks - When processing multiple files, use script blocks for better error handling
5. Verify dimensions first - Check image dimensions before processing to avoid unnecessary operations
6. Use appropriate resize flags - Consider using ! to force exact dimensions or ^ for minimum dimensions

Common Patterns

Pattern: Store ImageMagick Path

$magick = (Get-Command magick).Source

Pattern: Get Dimensions as Variables

$dimensions = & $magick identify -format "%w,%h" $_.FullName
$width,$height = $dimensions -split ','

Pattern: Conditional Processing

if ([int]$width -gt 1920) {
    & $magick $_.FullName -resize 1920x1080 $outputPath
}

Pattern: Create Thumbnails

& $magick $_.FullName -resize 427x240 "thumbnails/thumb_$($_.Name)"

Limitations

• Windows-specific paths (adjust for other operating systems)
• Requires ImageMagick to be installed (and ideally available as magick on PATH)
• Large batch operations may be memory-intensive
• Some complex operations may require additional ImageMagick delegates