# RemoveWatermark.dev — AI Sparkle Watermark Remover

> A free, 100% client-side browser tool that removes the visible ✨ sparkle watermark from images generated by Google Gemini AI. Built with vanilla JavaScript using a mathematically precise Reverse Alpha Blending algorithm. No server upload, no account, no cost — your images never leave your device.

## About

- **Tool name:** AI Sparkle Remover / Gemini Watermark Remover
- **Live URL:** https://removewatermark.dev/
- **Author:** Abhin Krishna (@dearabhin)
- **Source code:** https://github.com/dearabhin/gemini-watermark-remover
- **License:** MIT
- **Tech stack:** HTML5, Vanilla JavaScript (ES6 Modules), Tailwind CSS, JSZip

## What It Does

This tool solves a specific problem: Google Gemini AI adds a visible ✨ sparkle logo watermark to every image it generates. This tool reverses that watermark mathematically, restoring the original pixels with zero quality loss.

Key properties:
- Removes the **visible** Gemini sparkle logo watermark only
- Does **not** remove Google's invisible SynthID watermark (embedded steganographically)
- Supports PNG, JPG, and WebP image formats
- Supports batch processing of multiple images at once
- Outputs a ZIP file when downloading multiple processed images
- Processing happens entirely in the user's browser — no data is sent to any server

## How the Algorithm Works

Gemini applies its watermark using standard Alpha Compositing:

  Pixel_final = (α × Pixel_logo) + (1 − α) × Pixel_original

Where α is the watermark pixel's transparency (0.0–1.0) and Pixel_logo is pure white (255).

This tool reverses the formula:

  Pixel_original = (Pixel_final − α × Pixel_logo) / (1 − α)

It loads two bundled reference alpha-map images (bg_48.png for images ≤1024px, bg_96.png for larger images) to obtain the precise per-pixel α values, then applies the inverse formula across every watermark pixel.

## Important Usage Rule

The tool only works correctly with the **official downloaded file** from Gemini (via its Download button). It will not work correctly on:
- Screenshots of Gemini images
- Images saved via right-click "Save As" from the browser
- Re-compressed or re-exported copies

## Project Structure

- `/index.html` — Main application and UI
- `/js/app.js` — UI interaction and DOM manipulation
- `/js/engine.js` — Main processing controller (asset loading and orchestration)
- `/js/alphaMap.js` — Alpha transparency map extraction logic
- `/js/blendModes.js` — Reverse Alpha Blending math implementation
- `/assets/bg_48.png` — Reference watermark alpha map for small images (≤1024px)
- `/assets/bg_96.png` — Reference watermark alpha map for large images (>1024px)
- `/assets/og-image.jpg` — Social media Open Graph preview image

## FAQ

**Does this upload my images to a server?**
No. All processing is done locally inside the user's browser using the Canvas API. Images never leave the device.

**Which image formats are supported?**
PNG, JPG, and WebP images downloaded directly from Google Gemini AI.

**Does it remove the invisible SynthID watermark?**
No. This tool only removes the visible sparkle logo watermark. Google's invisible SynthID fingerprint remains intact.

**Is it free?**
Yes. Completely free, open source, and requires no account or subscription.

**Why must I use the Download button and not a screenshot?**
Screenshots re-compress pixel values, which changes the exact numeric pixel data the reverse formula depends on. The mathematical inversion requires lossless, unmodified pixel values from the original Gemini download.

**What is SynthID?**
SynthID is Google DeepMind's invisible, imperceptible watermarking system embedded into Gemini-generated images at the pixel level. It is detectable only by Google's proprietary classifier and is not affected by this tool.

## Links

- [Live Tool](https://removewatermark.dev/): The main watermark removal application
- [GitHub Repository](https://github.com/dearabhin/gemini-watermark-remover): Full open-source code with MIT license
- [Author on Twitter/X](https://twitter.com/dearabhin): Updates and announcements
- [Author on GitHub](https://github.com/dearabhin): Other projects by Abhin Krishna
- [Support on Patreon](https://www.patreon.com/cw/AbhinKrishna/membership): Help keep the tool free and maintained

## Optional

- [Original Alpha Compositing Algorithm Reference](https://github.com/allenk/GeminiWatermarkTool): The prior work this tool's algorithm is adapted from
- [Tailwind CSS CDN](https://cdn.tailwindcss.com): Styling framework used via CDN
- [JSZip Library](https://cdnjs.cloudflare.com/ajax/libs/jszip/3.10.1/jszip.min.js): Used for bundling multiple processed images into a ZIP download