Gemini Watermark vs SynthID: What Can (and Can't) Be Removed

People often ask whether removing the Gemini watermark makes an image "undetectable". It doesn't, because a Gemini image carries two different watermarks. One is the sparkle logo you can see. The other is SynthID, which you can't. This article explains both, how they differ, and exactly what a tool like DeGemini changes.

Quick answer

The Gemini watermark is a visible, semi-transparent sparkle in the bottom-right corner, and it can be removed exactly because it is blended in with a known formula. SynthID is an invisible watermark that Google DeepMind embeds in the pixels of the whole image; Google designed it to survive common edits, and removing the visible sparkle leaves it in place. A cleaned image can still be identified as AI-generated with Google's SynthID tools.

The two watermarks in a Gemini image

	Visible sparkle	SynthID
Can you see it?	Yes, a white four-pointed star	No, it is imperceptible
Where is it?	Bottom-right corner, 48 px or 96 px	Spread across the whole image
How is it added?	Alpha-blended on top of the finished image	Woven into the pixels as the image is generated
Who can detect it?	Anyone looking at the picture	Google's SynthID tools
Removed by DeGemini?	Yes, exactly	No

How the visible Gemini watermark works

The sparkle is a white logo laid over the image with partial transparency. For every pixel under the logo, the result is:

watermarked = original × (1 − α) + 255 × α

where α is the logo's opacity at that pixel. Google uses a 48 px sparkle on smaller images and a 96 px one on larger images, placed 32 px or 64 px from the bottom-right edges. Because α is fixed and can be measured once, the blend can be reversed: original = (watermarked − 255 × α) / (1 − α). That is why the Gemini watermark remover can restore the corner exactly instead of painting over it.

How SynthID works

SynthID is Google DeepMind's watermarking technology for AI-generated content. For images, it embeds a signal directly into the pixels while the image is created. The signal is designed to be imperceptible to people and, according to Google, to stay detectable after common changes such as cropping, adding filters, adjusting colours or brightness, and lossy compression.

SynthID is not a logo, and there is no single region to "erase". It doesn't change how the picture looks, so it doesn't affect image quality.

How to check whether an image was made with Google AI

Google offers SynthID-based verification. You can upload an image to the Gemini app and ask whether it was created or edited with Google AI, and Google runs a SynthID Detector portal for journalists and researchers. Results depend on Google's tools, not on the visible sparkle, which is why removing the logo doesn't change the answer.

What DeGemini changes, and what it doesn't

• Changes: only the pixels under the visible sparkle, which are recalculated to their original values.
• Does not change: every other pixel, and SynthID, which lives in the pixels across the whole image.
• File format: the result is a new PNG created in your browser, so file metadata from the original download is not copied over. SynthID is not metadata, so it stays.
• Privacy: nothing is uploaded; the image is processed locally with the Canvas API.

Want an image without a visible watermark from the start? Image to image AI edits a photo from a prompt, and the AI image generator creates one from text. Neither adds a visible logo, though images from Google's models still carry SynthID.

Using cleaned images responsibly

Removing the visible logo is an edit to your own image, but it doesn't change where the image came from. Some platforms and laws require AI-generated content to be labelled, especially in ads, political content and news. Label AI images where it's required, and never present them as real photographs to mislead people.

FAQ

Does removing the Gemini watermark remove SynthID? No. They are separate; the visible sparkle can be reversed, SynthID stays.

Can SynthID be removed? Google designed SynthID to survive common edits, and DeGemini makes no attempt to remove it.

Does SynthID lower image quality? No. It is invisible and doesn't change how the image looks.

Do all Gemini images have the visible sparkle? The sparkle is added to images from the Gemini app; some plans and developer tools produce images without it. SynthID is embedded in images from Google's image models either way.

Is the remover free? Yes, single images are free with no account. See how to remove the Gemini watermark for a step-by-step guide.