A professional-grade file protection tool that applies responsive watermarks to PDFs and images with advanced layout engines.
Install & Download
1. ClawHub CLI
The fastest way to install a skill directly from the registry.
npx clawhub@latest install universal-watermarker
2. Manual Installation
Copy the skill folder to one of these locations
~/.openclaw/skills/ <project>/skills/ Priority: Workspace > Local > Bundled
3. Prompt Installation
Copy this prompt to OpenClaw to install it automatically.
Help me install universal-watermarker using Clawhub. If Clawhub is not installed, install it first (npm i -g clawhub).
Prefer to download?
Get the raw skill files in a ZIP archive.
What is Universal Watermarker?
Universal Watermarker is a high-performance security utility designed for Openclaw Skills to handle document anti-counterfeiting. It supports mixed batch processing of PDF files and images, utilizing a built-in responsive layout engine that ensures perfect watermark placement regardless of document orientation or scale.
The tool solves common issues like garbled characters and shifting watermarks by using automatic font mapping and full internal resource embedding. Whether you are protecting internal confidential memos or branding public assets, this skill provides a seamless, developer-friendly way to automate file security.
Universal Watermarker Use Cases
- Protecting sensitive internal documents with diagonal confidential watermarks.
- Batch processing images for digital rights management and anti-theft.
- Full-page tiled watermarking for maximum anti-counterfeiting on legal documents.
- Automated dark/light mode watermarking based on document background brightness.
How Universal Watermarker Works
- The skill receives a list of file paths (PDFs or images) and the desired watermark text.
- It analyzes each document's dimensions and orientation to calculate the optimal scale and angle using trigonometric functions.
- The layout engine applies the watermark based on the selected mode (diagonal, center, or tile).
- If auto-adjust is enabled, the skill detects background brightness to select a high-contrast watermark color automatically.
- The processed file is generated with a prefix and saved to the original directory.
Universal Watermarker Setup
To use Universal Watermarker within Openclaw Skills, ensure you have Python 3.8+ installed and the required dependencies.
pip install pypdf reportlab Pillow
Place your desired .ttf or .ttc fonts in the ./fonts/ directory or specify a custom path in the parameters.
Universal Watermarker Data Schema & Taxonomy
Universal Watermarker follows a predictable I/O pattern for easy integration into automated workflows:
| Feature | Specification |
|---|---|
| Output Prefix | wm_ (e.g., example.pdf becomes wm_example.pdf) |
| Storage | Same directory as the source file |
| Supported Formats | PDF, JPG, PNG, WEBP |
| Font Support | TrueType (.ttf), TrueType Collection (.ttc) |
| Color Logic | Hex (#FFFFFF), RGB tuples (255,255,255), or Auto-Detection |
Universal Watermarker Advanced Features
- Smart diagonal scaling: Uses trigonometric calculations to ensure watermarks span from corner to corner perfectly on any aspect ratio.
- Ambient Brightness Sensing: Automatically toggles between light and dark watermarks based on document background analysis.
- Flexible Rendering Modes: Support for
diagonal(default),center(focal point), andtile(high-security full-page coverage). - LLM Semantic Mapping: Compatible with natural language triggers in Openclaw Skills like "make it subtle" (reduces opacity) or "protect this" (enables tile mode).
SKILL.md
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