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allenk/GeminiWatermarkTool

Offline C++ tool that removes visible Gemini watermarks from images via reverse alpha blending, with GUI, CLI and batch modes.

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What is it?

GeminiWatermarkTool removes the semi-transparent Gemini logo from images by inverting the alpha blending equation, so the original pixels are reconstructed rather than guessed by a generative model. It runs fully offline as a single portable executable with no external services, and supports JPG, PNG, WebP and BMP files.

The tool includes a desktop GUI with drag-and-drop, real-time before/after preview and batch processing, plus a command-line interface for scripts and pipelines. Watermark detection uses a three-stage normalized cross-correlation check with a confidence threshold, so images without a watermark can be skipped automatically. It also handles the newer Gemini 3.5 watermark layout and falls back to the legacy profile in the CLI.

Optional cleanup removes residual artifacts left after resizing or recompression, using OpenCV inpainting methods or an FDnCNN neural denoiser run through NCNN with Vulkan GPU acceleration and CPU fallback. Builds are available for Windows, Linux, macOS and Android, and the project provides a smaller CLI-only build.

Key features

  • 01Reverse alpha blending restores pixels mathematically, without generative inpainting.
  • 02Three-stage NCC detection skips images that have no watermark.
  • 03Desktop GUI with drag-and-drop, live preview and batch processing.
  • 04Command-line interface with batch directory mode and exit codes for scripting.
  • 05Optional AI denoise (FDnCNN via NCNN and Vulkan) and classic inpainting cleanup.
  • 06Runs offline as a self-contained executable on Windows, Linux, macOS and Android.

Use cases

  • Cleaning Gemini-generated slides, documents or screenshots where text must stay sharp.
  • Batch-processing a folder of AI-generated images in a script or CI pipeline.
  • Giving AI coding agents a watermark-removal tool through its MCP server or Claude Code skill.

Quick start

  1. 1

    Get the portable executable (zero runtime dependencies)

  2. 2

    Remove the watermark from an image with the CLI

    GeminiWatermarkTool image.png

Things to know

  • It targets Gemini visible watermarks only and is not a general-purpose inpainting tool.
  • Video watermark removal lives in a separate VeoWatermarkRemover demo repo, not this tool.
  • Optional AI denoise needs a Vulkan-capable GPU; otherwise the cleanup step is unavailable.

Topics

#watermark-removal#image-processing#cpp#alpha-blending#cli#gui#offline#computer-vision#cli-app#gemini

FAQ

What is GeminiWatermarkTool?
Offline C++ tool that removes visible Gemini watermarks from images via reverse alpha blending, with GUI, CLI and batch modes. GeminiWatermarkTool removes the semi-transparent Gemini logo from images by inverting the alpha blending equation, so the original pixels are reconstructed rather than guessed by a generative model. It runs fully offline as a single portable executable with no external services, and supports JPG, PNG, WebP and BMP files.
Is GeminiWatermarkTool free to use? What license does it have?
GeminiWatermarkTool is open source under the MIT license. Check the license terms before using it in commercial products.
Is GeminiWatermarkTool still maintained?
Updated within 6 months. The last commit to GeminiWatermarkTool was on Jul 28, 2026.
What can I use GeminiWatermarkTool for?
Cleaning Gemini-generated slides, documents or screenshots where text must stay sharp. Batch-processing a folder of AI-generated images in a script or CI pipeline. Giving AI coding agents a watermark-removal tool through its MCP server or Claude Code skill.
How do I install GeminiWatermarkTool?
Get the portable executable (zero runtime dependencies) Remove the watermark from an image with the CLI: GeminiWatermarkTool image.png
Where can I get GeminiWatermarkTool?
The source code and installation instructions are on GitHub: https://github.com/allenk/GeminiWatermarkTool

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