Reverse engineering Gemini's SynthID detection

andrewmcwatters

> We're actively collecting pure black and pure white images generated by Nano Banana Pro to improve multi-resolution watermark extraction. Oh hey, neat. I mentioned this specific method of extracting SynthID a while back.[1] Glad to see someone take it up. [1]: https://news.ycombinator.com/item?id=47169146#47169767

kelsey98765431

if you downscale then upscale it removes the watermark

armanj

kinda ironic you can clearly see signs of Claude, as it shows misaligning table walls in the readme doc

khernandezrt

Ok i get that eventually someone was gonna do this but why would we want to purposely remove one of the only ways of detecting if an image is ai generated or not...?

M4v3R

SynthID is visible in some generations (areas with a lot of edges, or text), I wonder if this would make them look better.

sodacanner

I don't understand all the handwringing. If it's this easy to remove SynthID from an AI-generated image then it wasn't a good solution in the first place.

doctorpangloss

Okay... this tests its own ability to remove the watermark against its own detector. It doesn't test against Gemini's SynthID app. So it does nothing...

Tiberium

Seems like a very low-quality AI-assisted research repo, and it doesn't even properly test against Google's own SynthID detector. It's not hard at all (with some LLM assistance, for example) to reverse-engineer network requests to be able to do SynthID detection without a browser instance or Gemini access, and then you'd have a ground truth.

coppsilgold

Inserting an undetectable 1-bit watermark into a multi megapixel image is not particularly difficult. If you assume competence from Google, they probably have two different watermarks. A sloppy one they offer an online oracle for and one they keep in reserve for themselves (and law enforcement requests). Also given that it's Google we are dealing with here, they probably save every single image generated (or at least its neural hash) and tie it to your account in their database.

m00dy

It's not really hard as it looks https://deepwalker.xyz/blog/bypassing-synthid-in-gemini-phot...

stevomacdaddy

Im confident i saw the watermark in use today, in nano banana, i copied the image from chrome into slack. the resulting upload was a black square with a red dot. and not the image i had generated.