ClearGem
Automatically removes visible watermarks from Google Gemini AI-generated images. Available as a Tampermonkey userscript and a Chrome/Firefox extension. Zero-click — just install and forget.
| Before | After |
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How It Works
Gemini stamps a semi-transparent white 4-pointed star logo in the bottom-right corner of every generated image using alpha compositing:
watermarked_pixel = alpha * 255 + (1 - alpha) * original_pixel
ClearGem reverses this mathematically to reconstruct the original pixels:
original_pixel = (watermarked_pixel - alpha * 255) / (1 - alpha)
Pre-calibrated alpha maps (48x48 and 96x96) are embedded directly. No AI inpainting, no server calls, no quality loss — pixel-perfect reconstruction with 99.9% accuracy (bounded only by 8-bit quantization).
Features
- Zero-click — images are cleaned automatically as they appear in chat
- Download interception — Gemini's download button delivers clean images
- Copy interception — Gemini's copy button copies clean images to clipboard
- Auto-detection — picks 48x48 or 96x96 watermark size based on image dimensions
- 100% client-side — nothing leaves your browser
- Toast notifications — subtle confirmation when images are cleaned
Install
Userscript (Tampermonkey / Greasemonkey)
- Install Tampermonkey (or any userscript manager)
- Download `cleargem.user.js` from the latest release — Tampermonkey will prompt to install
- Navigate to gemini.google.com — active immediately
Chrome Extension
- Download `ClearGem-v1.0.4.zip` from the latest release and unzip
- Go to
chrome://extensions, enable Developer mode - Click Load unpacked and select the unzipped folder
Or drag the .crx file onto the extensions page.
Firefox Extension
- Download `ClearGem-v1.0.4.xpi` from the latest release
- Go to
about:addons, click the gear icon, select Install Add-on From File
Compatibility
| Site | Userscript | Extension |
|---|---|---|
| gemini.google.com | Yes | Yes |
| aistudio.google.com | Yes | Yes |
Userscript works with Tampermonkey MV3 (@inject-into content). Extension is Manifest V3.
Limitations
- Removes the visible watermark only. Does not remove SynthID — Google's invisible steganographic watermark embedded at the pixel generation level. That requires diffusion model re-processing and is a fundamentally different problem.
- If Google changes the watermark pattern, position, or alpha values, the embedded alpha maps will need updating.
Credits
Reverse alpha blending method and calibrated watermark masks based on GeminiWatermarkTool by Allen Kuo (MIT License). Alpha map data sourced from gemini-watermark-remover.
License
MIT