About
The free tool that removes
Gemini watermarks precisely.
Browser-only. Free forever. Mathematically precise - not AI guessing.
What is GeminiErase?
GeminiErase is a free, browser-based tool that removes the visible 4-pointed star watermark from images generated by Google Gemini and Nano Banana (Gemini Flash Image). The tool processes images entirely within your web browser - no server, no upload, no account required.
Processing completes in under 2 milliseconds using a mathematical reverse alpha blending algorithm. Unlike AI inpainting tools, GeminiErase calculates the exact original pixel values rather than guessing, achieving 99.9% pixel accuracy.
The tool is free forever, works on PNG, JPG, and WEBP images, and has no usage limits.
Why We Built This
We use Gemini regularly to generate images for creative and professional work. The visible watermark - while understandable as a product identifier - often interferes with the final output when images are used in design, presentation, or publication contexts.
Existing solutions fell into one of two categories: tools that required uploading your image to a third-party server (a privacy problem), or AI inpainting tools that "hallucinated" new pixels to fill the watermark area (an accuracy problem). Neither was acceptable.
Since the Gemini watermark is composited using a known mathematical formula (alpha blending), we realized it could be removed mathematically - not guessed. So we built GeminiErase: a tool that solves the alpha blending equation in reverse, in your browser, with no data leaving your device.
How It Works
The Gemini watermark is added to images using a process called alpha blending: the visible mark is composited onto the image using a known mathematical formula where each pixel becomes a weighted mix of the original image pixel and the watermark overlay pixel.
Because the blending formula is known, and because the watermark's shape and alpha (transparency) values are fixed, GeminiErase can run the formula backwards to calculate the exact original pixel value underneath each watermark pixel.
In plain terms
- 1.Your image is loaded into a browser canvas
- 2.A Web Worker scans the bottom-right area for the watermark template using normalized cross-correlation
- 3.The matched region is processed pixel by pixel using inverse alpha blending math
- 4.The result is encoded as a PNG and made available for download
- 5.Nothing leaves your browser at any step
Our Commitment to Privacy
Privacy is not a feature we added - it is the architecture of the tool:
- -Your images are never uploaded to any server
- -We have no user accounts, so we cannot store your data even if we wanted to
- -We do not use tracking cookies or analytics on the tool
- -No AI model inference - no data is sent to any AI service
- -The entire processing pipeline runs in your browser tab and is discarded when you close it
The Technology
Canvas API
Decodes images to raw RGBA pixel data for processing
Web Workers
Runs detection and removal on a background thread so your browser stays responsive
Reverse Alpha Blending
The core math: solves the compositing equation backwards to recover original pixels
48x48 and 96x96 Alpha Templates
Precomputed watermark shape maps used for precise detection via normalized cross-correlation (NCC)
Nano Banana Support
Detects the same Gemini-star watermark as used by Nano Banana (Gemini Flash Image)
Multi-scale Detection
Dynamically generates size variants based on image dimensions to handle mobile compression and cropping