Can Witness detect Gemini and Nano Banana images images?
Google's image models are a mixed case. A recent Gemini image model was held out of Witness's training data, so pixel-based detection is less certain. Witness also checks for Google's SynthID watermark, which can give a stronger signal when it is present.
Google adds a SynthID watermark to images from its generators. Witness checks for it, and also reads C2PA data when present. Edits and re-encoding can weaken a watermark.
What helps and what hurts
What helps
- Use the SynthID check on the original file.
- Check Content Credentials.
- Read the explanation, which says which signals fired.
Where detection gets harder
- A missing watermark does not mean an image is real.
- Screenshots, heavy compression and resizing remove the traces detectors rely on, and can also make real photos look suspicious.
- New versions of a generator can be missed until detection is updated.
How to read this page
- Coverage statements come from Witness's own internal evaluation, not an independent benchmark.
- No accuracy percentage is published for this generator.
- Witness reports a likelihood with a confidence score. It does not prove anything on its own.
How it works
- 01
Drop in the file
Upload an image or video, or paste a link, or right click any image in Chrome with the extension.
- 02
Witness checks it
Several detection methods run in parallel, plus checks for provenance data such as Content Credentials and metadata.
- 03
Read the result
You get a likely real or likely AI-generated verdict with a confidence percentage and a plain-language explanation.
Frequently asked questions
Can Witness detect Gemini images?
It checks for the SynthID watermark and runs AI detection. The watermark is a strong signal when found. Pixel detection of the newest Google models is less certain.
Does Witness replace Google's own SynthID tools?
No. Witness surfaces what it can check. See the SynthID detector page for what is and is not publicly available.
Is a Witness result proof?
No. Witness gives a likelihood and a confidence percentage, plus an explanation. Use it as a second pair of eyes, not as a final ruling.
Related
Don't guess. Witness it.
Free to try. No account needed for your first scans. Witness gives a likelihood with a confidence percentage, not a certainty.