unmark

Strip Google Gemini's watermark from generated images. Fast, local, no API.

unmark is a command-line tool that removes the small sparkle Google Gemini stamps in the bottom-right corner of every image it generates. It works fully offline using deterministic image-processing strategies — no cloud calls, no API keys, no telemetry.

Example

A real Gemini-generated image, before and after unmark --tool gemini:

Before	After

Why

Gemini stamps a small watermark on every image it generates. Generic inpainting tools either leave visible artifacts, demand manual masking, or send your image to a remote server. unmark knows exactly where the Gemini sparkle sits and removes it cleanly with image symmetry + content-aware fill — locally, in seconds.

Install

pip install unmark

Or from source:

git clone https://github.com/verepdev/unmark.git
cd unmark
pip install -e .

Requires Python 3.10+.

Usage

Single image

unmark input.png -o output.png

Tool-specific preset

unmark gemini-output.png -o clean.png --tool gemini

Batch

unmark *.png --batch -o cleaned/

Custom strategy

# Mirror-patch from another corner
unmark img.png -o out.png --strategy mirror --corner bottom-right --source bottom-left

# Targeted inpaint
unmark img.png -o out.png --strategy inpaint --threshold 120

How it works

unmark ships three strategies, picked automatically based on the watermark's properties:

Strategy	Best for	How it works
mirror	Watermarks in a corner of a near-uniform background (Gemini sparkle)	Copies the symmetric patch from the opposite corner, mirrors it, blends with feathered edges
inpaint	Watermarks with detectable color contrast	Builds a brightness/color mask, runs OpenCV TELEA inpainting on detected pixels
hybrid	Complex backgrounds	Mirror-patch first, then targeted inpaint on residual artifacts

Tool presets bundle the right strategy + parameters for known watermark patterns.

What it handles

Mode	What it does
--tool gemini	Removes the bottom-right sparkle/diamond Gemini stamps on every generated image
Generic flags	`--strategy mirror

Legal & ethics

This tool is intended for personal use with images you generated yourself. Removing watermarks from images you do not own may violate the source tool's terms of service. You are responsible for how you use this tool.

Contributing

Issues and PRs welcome, especially:

• Better strategies for non-uniform backgrounds
• Performance improvements
• Tests on edge cases (small images, very dense backgrounds, etc.)
• A preset for another AI tool you actually use — open an issue first so we can discuss the approach before you write code

Dev setup:

git clone https://github.com/verepdev/unmark.git
cd unmark
python -m venv .venv && source .venv/bin/activate  # or .venv\Scripts\activate on Windows
pip install -e ".[dev]"
pre-commit install   # enable format + lint hook on every commit
pytest

Code style: Ruff for lint, type hints on public functions, short focused functions.

License

MIT — by @verepdev.