Gemini Watermark Remover

Remove the visible Gemini AI watermark (star/sparkle logo) from generated images using mathematically accurate reverse alpha blending.

Fully offline — pure Python, no external binary downloads, no network access.

When to Use

• - Remove the Gemini watermark from AI-generated images
• Batch process a directory of Gemini-generated images
• Clean images before publishing or sharing
• Automate watermark removal in pipelines

Quick Start

Install Dependencies (one-time)

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Requires: Python ≥ 3.9. No Rust toolchain, no compiled binaries, no downloads.

Basic Usage

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How It Works

Gemini adds a semi-transparent white star/sparkle logo to generated images using alpha blending:

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This tool reverses the equation to recover the original pixels:

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The alpha map (watermark transparency pattern) is generated mathematically as a
4-pointed star (central Gaussian core + 4 elongated cardinal rays) at two sizes:

• - 48×48 with 32 px margin — images where either dimension ≤ 1024 px
• 96×96 with 64 px margin — images where both dimensions > 1024 px

For improved accuracy you can supply your own alpha map derived from a background
capture of the Gemini watermark on a white background (--alpha-map).

Detection

Before removal, a three-stage algorithm checks whether a watermark is present:

1. 1. Spatial NCC (50% weight) — normalised cross-correlation with the alpha map
2. Gradient NCC (30% weight) — edge signature matching via Sobel operators
3. Variance Analysis (20% weight) — texture dampening detection

Images without detected watermarks are automatically skipped.

CLI Parameters

Supported Formats

Usage Examples

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Deriving a Custom Alpha Map

For pixel-perfect removal, capture the Gemini watermark on a pure white
background and compute:

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Save the result as a grayscale PNG and pass it via --alpha-map.

Output

• - Single file — saves to -o path, or {name}_cleaned.{ext} by default
• Directory — saves all processed images to the output directory
• Skipped images — images without detected watermarks are not modified (unless --force)
• Exit code — 0 on success, 1 if any image fails

Troubleshooting

"No watermark detected" on a watermarked image

• - Try lowering the threshold: INLINECODE26
• Or bypass detection entirely: INLINECODE27
• Consider supplying a custom alpha map for your watermark variant

Image looks distorted after removal

• - The image may not have a Gemini watermark. Use detection (avoid --force)
• Try --force-small or --force-large to match the correct size
• Supply a custom alpha map for better precision

"Image too small" warning

The image dimensions are smaller than the watermark region. This typically
means the image does not have a Gemini watermark.

ModuleNotFoundError: Pillow or numpy

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Limitations

• - Visible watermark only — this tool removes the visible star/sparkle logo watermark
• Cannot remove SynthID — Google's invisible watermark (SynthID) is embedded at the pixel level during generation and cannot be reversed
• Fixed position only — handles watermarks in the standard bottom-right position only
• Built-in alpha map is approximate — use --alpha-map with a captured reference for exact results