gemini-watermark-remover

# Gemini Watermark Remover

Remove visible Gemini AI watermarks (star/sparkle logo) from generated images using mathematically accurate reverse alpha blending.

**Fully offline — pure Python, local processing only, images are not uploaded.**

## When to Use

- Remove watermark from Gemini AI generated images
- Clean images before publishing or sharing
- Batch process multiple images

## Quick Start

### Install Dependencies (one-time)

```bash
pip install Pillow numpy
```

### Usage

```bash
# Single image (auto-detect watermark)
python3 scripts/remove_watermark.py photo.jpg

# Specify output path
python3 scripts/remove_watermark.py photo.jpg -o clean_photo.jpg

# Force removal without detection
python3 scripts/remove_watermark.py photo.jpg -o clean.jpg --force
```

## How It Works

Gemini adds watermark using alpha blending:

```
watermarked = alpha * 255 + (1 - alpha) * original
```

Reverse the equation:

```
original = (watermarked - alpha * 255) / (1 - alpha)
```

### Detection Rules

| Image Size | Watermark Size | Right Margin | Bottom Margin |
|------------|---------------|--------------|---------------|
| Width > 1024 AND Height > 1024 | 96×96 | 64px | 64px |
| Otherwise | 48×48 | 32px | 32px |

## Key Points

- Uses built-in watermark templates (`assets/bg_48.png` / `assets/bg_96.png`)
- Alpha map = max RGB channel value (not alpha channel)
- Includes noise filtering (ALPHA_NOISE_FLOOR)
- Pure mathematical method, pixel-level accuracy

## Limitations

- Removes only visible watermark (bottom-right semi-transparent logo)
- Cannot remove invisible watermarks (e.g., SynthID)
- Designed for current Gemini watermark pattern

## Dependencies

- Python 3
- Pillow (PIL)
- NumPy

# Gemini Watermark Remover

[English](./README.md) | [中文](./README_zh.md)

---

Remove visible Gemini AI watermarks from images using reverse alpha blending algorithm.

## ⚠️ Disclaimer

**This tool is for personal learning and research only. Commercial use is prohibited.**

## Features

- ✅ Pure local processing (images not uploaded)
- ✅ Reverse alpha blending algorithm, lossless watermark removal
- ✅ Automatic watermark size detection (48×48 or 96×96)
- ✅ Standalone script with embedded templates (no external dependencies)

## Installation

```bash
pip install Pillow numpy
```

## Usage

```bash
# Basic usage
python3 scripts/remove_watermark.py image.jpg

# Specify output
python3 scripts/remove_watermark.py image.jpg -o cleaned.jpg
```

## Algorithm

Gemini uses alpha blending:
```
watermarked = α × 255 + (1 - α) × original
```

Reverse:
```
original = (watermarked - α × 255) / (1 - α)
```

## Files

```
├── scripts/
│   └── remove_watermark.py   # Main script with embedded templates
├── requirements.txt
├── README.md
├── README_zh.md
└── LICENSE
```

## License

[MIT License](./LICENSE)