# Imagemagick

> >

- **Type:** Skill
- **Install:** `agentstack add skill-jie-meng-mythril-agent-skills-imagemagick`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [jie-meng](https://agentstack.voostack.com/s/jie-meng)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [jie-meng](https://github.com/jie-meng)
- **Source:** https://github.com/jie-meng/mythril-agent-skills/tree/main/mythril_agent_skills/skills/imagemagick

## Install

```sh
agentstack add skill-jie-meng-mythril-agent-skills-imagemagick
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# When to Use This Skill

- User asks to resize, crop, rotate, or transform images
- User asks to convert images between formats (PNG, JPEG, WebP, GIF, SVG, etc.)
- User asks to create thumbnails or responsive image variants
- User asks to add watermarks, borders, text overlays, or frames
- User asks to apply effects/filters (blur, sharpen, grayscale, sepia, etc.)
- User asks to batch process or bulk-transform multiple images
- User asks to get image dimensions, metadata, or file info
- User asks to optimize/compress images for web
- User mentions "imagemagick", "magick", or any image manipulation task

# Prerequisites

Requires `magick` CLI (ImageMagick v7+) installed and on PATH.

**Verify installation:**

```bash
magick -version
```

**Install if missing:**

- macOS: `brew install imagemagick`
- Ubuntu/Debian: `sudo apt-get install imagemagick`
- Windows: Download from https://imagemagick.org/script/download.php

> On older systems with ImageMagick 6.x, use `convert` instead of `magick`.

# Workflow

## 1) Pre-flight check

Verify `magick` is available before running any operation:

```bash
command -v magick &> /dev/null || { echo "ImageMagick not found. Install: brew install imagemagick (macOS) or sudo apt-get install imagemagick (Linux)"; exit 1; }
```

## 2) Determine the operation

Identify what the user needs from these categories:

| Category | Operations |
|---|---|
| Info | Dimensions, metadata, format, color space |
| Convert | Format conversion, quality settings |
| Resize | Scale, fit, fill, percentage |
| Crop | Region extraction, center crop, aspect ratio crop |
| Thumbnail | Resize + crop for fixed dimensions |
| Effects | Blur, sharpen, grayscale, sepia, negate, edge, emboss |
| Adjust | Brightness, contrast, saturation, hue, auto-level |
| Transform | Rotate, flip, flop, auto-orient |
| Overlay | Text, watermarks, compositing, borders |
| Batch | mogrify or shell loops for multiple files |
| Animate | GIF creation, optimization, frame extraction |

## 3) Determine output filename

**Default: write to a new file, never overwrite the original.**

- If the user did NOT say to overwrite or modify in-place → generate a descriptive output filename in the same directory (e.g. `photo_resized.jpg`, `banner_gray.png`).
- If the user explicitly asks to overwrite (e.g. "覆盖", "replace", "in-place", "same name", "原图修改") → output to the same filename or use `mogrify`.
- For format conversion the extension naturally changes, so `photo.png` → `photo.jpg` already preserves the original.
- For batch operations, prefer outputting to a subdirectory (`mkdir -p output && mogrify -path ./output ...`) unless the user says to overwrite.

## 4) Execute the operation

### Geometry Specifications

ImageMagick uses geometry strings for dimensions:

| Syntax | Meaning |
|---|---|
| `100x100` | Fit within 100×100 (maintains aspect ratio) |
| `100x100!` | Force exact size (ignores aspect ratio) |
| `100x100^` | Fill 100×100 (may exceed, maintains aspect ratio) |
| `100x` | Width 100, auto height |
| `x100` | Height 100, auto width |
| `50%` | Scale to 50% |
| `100x100+10+20` | 100×100 region at offset (10, 20) |

### Format Conversion

```bash
# Basic conversion (format inferred from extension)
magick input.png output.jpg

# With quality control
magick input.png -quality 85 -strip output.jpg

# To WebP
magick input.jpg -quality 80 output.webp

# Lossless WebP
magick input.png -define webp:lossless=true output.webp

# Progressive JPEG (better for web)
magick input.png -quality 85 -interlace Plane -strip output.jpg
```

### Resizing

```bash
# Fit within dimensions (maintains aspect ratio)
magick input.jpg -resize 800x600 output.jpg

# Width only (auto height)
magick input.jpg -resize 800x output.jpg

# Height only (auto width)
magick input.jpg -resize x600 output.jpg

# Exact dimensions (ignores aspect ratio)
magick input.jpg -resize 800x600! output.jpg

# Scale by percentage
magick input.jpg -resize 50% output.jpg

# Shrink only (don't enlarge)
magick input.jpg -resize '800x600>' output.jpg

# Enlarge only (don't shrink)
magick input.jpg -resize '800x600<' output.jpg
```

### Cropping

```bash
# Crop region at offset
magick input.jpg -crop 400x400+100+100 +repage output.jpg

# Center crop
magick input.jpg -gravity center -crop 400x400+0+0 +repage output.jpg
```

### Thumbnail Generation (Resize + Crop)

```bash
# Square thumbnail from any aspect ratio
magick input.jpg -resize 200x200^ -gravity center -extent 200x200 thumb.jpg

# With specific background for padding
magick input.jpg -resize 200x200 -background white -gravity center -extent 200x200 thumb.jpg
```

### Effects and Filters

```bash
# Blur
magick input.jpg -blur 0x8 output.jpg

# Sharpen
magick input.jpg -sharpen 0x1 output.jpg

# Grayscale
magick input.jpg -colorspace Gray output.jpg

# Sepia tone
magick input.jpg -sepia-tone 80% output.jpg

# Negate (invert)
magick input.jpg -negate output.jpg

# Edge detection
magick input.jpg -edge 3 output.jpg

# Oil painting
magick input.jpg -paint 4 output.jpg

# Charcoal drawing
magick input.jpg -charcoal 2 output.jpg
```

### Adjustments

```bash
# Brightness and contrast
magick input.jpg -brightness-contrast 10x20 output.jpg

# Saturation (modulate: brightness, saturation, hue)
magick input.jpg -modulate 100,150,100 output.jpg

# Auto-level (normalize contrast)
magick input.jpg -auto-level output.jpg

# Auto-orient based on EXIF
magick input.jpg -auto-orient output.jpg

# Strip metadata (reduce file size)
magick input.jpg -strip output.jpg
```

### Rotation and Flipping

```bash
# Rotate 90° clockwise
magick input.jpg -rotate 90 output.jpg

# Rotate with background color
magick input.jpg -background white -rotate 45 output.jpg

# Flip vertically
magick input.jpg -flip output.jpg

# Mirror horizontally
magick input.jpg -flop output.jpg
```

### Borders and Frames

```bash
# Add border
magick input.jpg -bordercolor black -border 10x10 output.jpg

# Add shadow
magick input.jpg \( +clone -background black -shadow 80x3+5+5 \) \
  +swap -background white -layers merge +repage output.jpg
```

### Text and Watermarks

```bash
# Add text
magick input.jpg -gravity south -pointsize 20 -fill white \
  -annotate +0+10 "Copyright 2025" output.jpg

# Semi-transparent watermark
magick input.jpg \( -background none -fill "rgba(255,255,255,0.5)" \
  -pointsize 50 label:"DRAFT" \) -gravity center -compose over -composite output.jpg

# Image watermark (bottom-right)
magick input.jpg watermark.png -gravity southeast \
  -geometry +10+10 -composite output.jpg
```

### Compositing

```bash
# Side-by-side
magick input1.jpg input2.jpg +append output.jpg

# Stack vertically
magick input1.jpg input2.jpg -append output.jpg

# Overlay
magick input.jpg overlay.png -gravity center -compose over -composite output.jpg
```

### Image Information

```bash
# Basic info
magick identify image.jpg

# Dimensions only
magick identify -format "%wx%h" image.jpg

# Detailed info
magick identify -verbose image.jpg

# Format string: filename, size, format
magick identify -format "%f: %wx%h %b %m\n" image.jpg
```

Common format tokens: `%f` filename, `%w` width, `%h` height, `%b` file size, `%m` format, `%[colorspace]` colorspace, `%[depth]` bit depth.

### Batch Processing

**Using mogrify (prefer `-path` to preserve originals):**

```bash
# Resize all JPEGs to output directory (originals preserved)
mkdir -p resized
mogrify -path ./resized -resize 800x600 *.jpg

# Convert all PNGs to JPEG (output directory preserves originals)
mkdir -p output
mogrify -path ./output -format jpg -quality 85 -strip *.png

# Batch thumbnails
mkdir -p thumbnails
mogrify -path ./thumbnails -resize 200x200^ -gravity center \
  -crop 200x200+0+0 +repage *.jpg

# In-place overwrite (ONLY when user explicitly requests it)
mogrify -resize 800x600 *.jpg
```

**Using shell loops (more control):**

```bash
# Responsive image variants
for size in 320 640 1024 1920; do
  magick input.jpg -resize ${size}x -quality 85 "output-${size}w.jpg"
done

# Convert with custom naming
for img in *.png; do
  magick "$img" -quality 90 "${img%.png}.jpg"
done
```

### Animated GIFs

```bash
# Create GIF from frames
magick -delay 100 -loop 0 frame*.png animated.gif

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

# Extract frames
magick animated.gif frame_%03d.png
```

### Contact Sheets (Montage)

```bash
# Basic grid with labels
montage *.jpg -geometry 200x200+5+5 -label '%f' contact-sheet.jpg

# 3-column layout
montage *.jpg -tile 3x -geometry 200x200+5+5 contact-sheet.jpg
```

## 5) Performance Tips

```bash
# Limit memory for large images
magick -limit memory 2GB -limit map 4GB input.jpg -resize 50% output.jpg

# Set thread count
magick -limit thread 4 input.jpg -resize 50% output.jpg
```

### Web Optimization Quick Reference

| Goal | Command flags |
|---|---|
| High quality | `-quality 95` |
| Balanced (recommended) | `-quality 85 -strip` |
| Smaller file | `-quality 70 -sampling-factor 4:2:0 -strip` |
| Progressive JPEG | `-quality 85 -interlace Plane -strip` |

# Guidelines

1. **Preserve original files by default.** Unless the user explicitly asks to overwrite the original (e.g. "覆盖原图", "replace in-place", "modify the original", "same filename"), ALWAYS output to a new filename in the same directory. Naming conventions:
   - Resize: `photo.jpg` → `photo_800x600.jpg`
   - Convert: `photo.png` → `photo.jpg`
   - Effect: `photo.jpg` → `photo_blur.jpg`, `photo_gray.jpg`
   - Thumbnail: `photo.jpg` → `photo_thumb.jpg`
   - General: `photo.jpg` → `photo_processed.jpg`
   - Batch: output to a subdirectory (e.g. `resized/`, `thumbnails/`) or add a prefix/suffix to each filename

   Only use `mogrify` (in-place modification) when the user explicitly requests overwriting originals. When using `mogrify` for batch operations, prefer `-path ./output_dir` to preserve originals.

2. **Always quote file paths** that might contain spaces
3. **Use `+repage`** after crop to reset virtual canvas
4. **Use `-strip`** to remove metadata when optimizing for web
5. **Use `-auto-orient`** to respect EXIF orientation before processing
6. **Test on a sample** before running batch operations
7. **Set quality explicitly** — default is lossless for some formats, which means large files
8. **Use progressive JPEG** (`-interlace Plane`) for web delivery

# Troubleshooting

**"magick: not found"** — ImageMagick not installed or not on PATH. Install via `brew install imagemagick` (macOS) or `sudo apt-get install imagemagick` (Linux).

**"not authorized"** — ImageMagick security policy blocking the operation. Check/edit `/etc/ImageMagick-7/policy.xml`.

**"no decode delegate"** — Missing format support library (libjpeg, libpng, libwebp). Install the missing library and reinstall ImageMagick.

**"memory allocation failed"** — Image too large. Use `-limit memory` and `-limit map` flags, or process in smaller chunks.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [jie-meng](https://github.com/jie-meng)
- **Source:** [jie-meng/mythril-agent-skills](https://github.com/jie-meng/mythril-agent-skills)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-jie-meng-mythril-agent-skills-imagemagick
- Seller: https://agentstack.voostack.com/s/jie-meng
- Browse the marketplace: https://agentstack.voostack.com/browse

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