Gemini Watermark Remover: Fast Client‑Side Open‑Source Tool

Gem­ini Watermark Remover: Fast Client‑Side Open‑Source Tool

When Gemini AI started embedding a semi‑transparent logo into every generated image, creators quickly found themselves fighting for a clean visual output. Traditional solutions rely on AI inpainting or complex server‑side pipelines, both of which can degrade quality and raise privacy concerns.

Enter Gemini Watermark Remover, a lightweight, 100 % client‑side JavaScript tool that restores images to their original, watermark‑free state using a Reverse Alpha Blending formula.

Why Reverse Alpha Blending?

Gemini’s watermark algorithm follows a simple alpha compositing rule:

watermarked = α × logo + (1 – α) × original

Where α is the transparency map of the logo. The remover inverts this equation to recover the original pixel values:

original = (watermarked – α × logo) / (1 – α)

Because the logo is always the white diamond shape on a dark background, the algorithm can compute the exact alpha map from a pre‑captured watermark image, achieving lossless restoration without any machine‑learning hallucinations.

Key Features

• 100 % Client‑Side – Everything runs in the browser; no data leaves your machine.
• Privacy‑First – Images are never uploaded; your creative work stays local.
• Fast & Lightweight – Under 200 KB minified, it processes high‑resolution images in milliseconds.
• Auto‑Detection – Detects 48×48 or 96×96 watermark variants and correctly adjusts to image dimensions.
• Drag‑and‑Drop UI – One‑click processing with instant download of the cleaned image.
• Userscript for Gemini – Install a Tampermonkey script to remove watermarks directly from the Gemini conversation page.
• API for Developers – Import removeWatermark as an npm module and integrate into your own tooling.

How to Use

1. Online Demo – Visit https://banana.ovo.re, drag and drop a Gemini image, and click “Download”.
2. Userscript – In Tampermonkey, add the script from the repo. After installation, open any Gemini chat thread and click the new “Copy Image” button to get a watermark‑free copy.
3. Local Build – Clone the repo, run pnpm install, then pnpm dev for a local preview.

Technical Overview

// alphaMap.js
export function calculateAlphaMap(imageData) {
  const alpha = new Float32Array(imageData.width * imageData.height);
  // compute alpha from max RGB channel
  return alpha;
}

// blendModes.js
export function removeWatermark(imageData, alphaMap) {
  const data = imageData.data;
  for (let i = 0; i < data.length; i += 4) {
    const alpha = Math.min(alphaMap[i / 4] || 1, 0.95);
    const original = (data[i] - alpha * 255) / (1 - alpha);
    data[i] = Math.min(255, Math.max(0, original));
  }
}

The source is fully documented and follows ES6 modules, Canvas API, and modern typed arrays for performance.

Security & Legal

• The app runs completely in your browser; no data is sent to external servers.
• The tool is released under the MIT license and is meant for personal and educational use only. Users are responsible for ensuring compliance with local laws and platform terms of service.

Where to Find It

Community & Contribution

The project welcomes contributions: bug fixes, new watermark variants, or language localizations. Feel free to open an issue or submit a pull request.

Bottom Line

Gemini Watermark Remover demonstrates how math can replace machine‑learning in a niche but impactful problem. By leveraging a simple, well‑understood reverse blending algorithm, it delivers fast, privacy‑preserving watermark removal with 100 % accuracy. If you’re dealing with Gemini‑generated images, this open‑source tool is worth adding to your toolkit.