image-manipulation-image-magick

What this skill does

# 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

## Usage Examples

### Example 0: Resolve `magick` executable

**PowerShell (Windows):**
```powershell
# 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."
}
```

**Bash (Linux/macOS):**
```bash
# Check if magick is available on PATH
if ! command -v magick &> /dev/null; then
    echo "ImageMagick not found. Install it using your package manager:"
    echo "  Ubuntu/Debian: sudo apt install imagemagick"
    echo "  macOS: brew install imagemagick"
    exit 1
fi
```

### Example 1: Get Image Dimensions

**PowerShell (Windows):**
```powershell
# 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 
}
```

**Bash (Linux/macOS):**
```bash
# For a single image
magick identify -format "%wx%h" path/to/image.jpg

# For multiple images
for img in path/to/images/*; do
    magick identify -format "%f: %wx%h\n" "$img"
done
```

### Example 2: Resize Images

**PowerShell (Windows):**
```powershell
# 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)"
}
```

**Bash (Linux/macOS):**
```bash
# Resize a single image
magick input.jpg -resize 427x240 output.jpg

# Batch resize images
for img in path/to/images/*; do
    filename=$(basename "$img")
    magick "$img" -resize 427x240 "path/to/output/thumb_$filename"
done
```

### Example 3: Get Detailed Image Information

**PowerShell (Windows):**
```powershell
# Get verbose information about an image
& $magick identify -verbose path/to/image.jpg
```

**Bash (Linux/macOS):**
```bash
# Get verbose information about an image
magick identify -verbose path/to/image.jpg
```

### Example 4: Process Images Based on Dimensions

**PowerShell (Windows):**
```powershell
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)"
        }
    }
}
```

**Bash (Linux/macOS):**
```bash
for img in path/to/images/*; do
    dimensions=$(magick identify -format "%w,%h" "$img")
    if [[ -n "$dimensions" ]]; then
        width=$(echo "$dimensions" | cut -d',' -f1)
        height=$(echo "$dimensions" | cut -d',' -f2)
        if [[ "$width" -eq 2560 || "$height" -eq 1440 ]]; then
            filename=$(basename "$img")
            echo "Processing $filename"
            magick "$img" -resize 427x240 "path/to/output/thumb_$filename"
        fi
    fi
done
```

## Guidelines

1. **Always quote file paths** - Use quotes around file paths that might contain spaces
2. **Use the `&` operator (PowerShell)** - Invoke the magick executable using `&` in PowerShell
3. **Store the path in a variable (PowerShell)** - Assign the ImageMagick path to `$magick` for cleaner code
4. **Wrap in loops** - When processing multiple files, use `ForEach-Object` (PowerShell) or `for` loops (Bash)
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

### PowerShell Patterns

#### Pattern: Store ImageMagick Path

```powershell
$magick = (Get-Command magick).Source
```

#### Pattern: Get Dimensions as Variables

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

#### Pattern: Conditional Processing

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

#### Pattern: Create Thumbnails

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

### Bash Patterns

#### Pattern: Check ImageMagick Installation

```bash
command -v magick &> /dev/null || { echo "ImageMagick required"; exit 1; }
```

#### Pattern: Get Dimensions as Variables

```bash
dimensions=$(magick identify -format "%w,%h" "$img")
width=$(echo "$dimensions" | cut -d',' -f1)
height=$(echo "$dimensions" | cut -d',' -f2)
```

#### Pattern: Conditional Processing

```bash
if [[ "$width" -gt 1920 ]]; then
    magick "$img" -resize 1920x1080 "$outputPath"
fi
```

#### Pattern: Create Thumbnails

```bash
filename=$(basename "$img")
magick "$img" -resize 427x240 "thumbnails/thumb_$filename"
```

## 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)