ai-watermark-remover

Remove AI-generated watermarks from images. Currently supports Google Gemini (Nano Banana) watermarks.

How it works

Gemini adds watermarks using alpha blending: watermarked = α × logo + (1 - α) × original

This tool reverses the process: original = (watermarked - α × logo) / (1 - α)

The alpha map is extracted from known watermark patterns (48×48 for images ≤1024px, 96×96 for larger).

Installation

# Global install from npm
npm i -g ai-watermark-remover

# Or run directly without installing
npx ai-watermark-remover image.jpg

Usage

CLI

# Process single file (overwrites original)
ai-watermark-remover image.jpg

# Save to different file
ai-watermark-remover image.jpg cleaned.jpg

# Process entire directory
ai-watermark-remover ./images/

# Force watermark size detection
ai-watermark-remover image.jpg -s small   # 48×48
ai-watermark-remover image.jpg -s large   # 96×96

As a library

import { removeWatermark, removeWatermarkFromFile } from 'ai-watermark-remover';

// From file to file
await removeWatermarkFromFile('input.jpg', 'output.jpg');

// From buffer (useful for APIs/servers)
const cleanedBuffer = await removeWatermark(imageBuffer);

Supported formats

• JPEG (.jpg, .jpeg)
• PNG (.png)
• WebP (.webp)
• BMP (.bmp)

Limitations

• Only works with Gemini watermarks (other AI tools use different patterns)
• Best results with lossless formats (PNG, WebP lossless)
• JPEG compression may reduce quality of removal
• Won't work if image was cropped/rotated after watermark was added

Credits

Algorithm based on GeminiWatermarkTool by AllenK.

License

MIT