“No neural networks. No proprietary access,” Aloshdenny said on Medium. “Turns out if you’re unemployed and average enough ‘pure black’ AI-generated images, every nonzero pixel is literally just the watermark staring back at you.”

SynthID is a near-invisible watermarking system that tags content generated by Google’s AI tools, embedding itself in the pixels of images at the point of creation. It was designed to be difficult to remove without degrading the image quality, and is used widely across the AI products offered by Google — everything spat out by models like Nano Banana and Veo 3 carries SynthID watermarks, and it’s even being applied to YouTube’s AI-generated creator clones.

Aloshdenny says he found the system to be “genuinely good engineering,” and was still unable to remove SynthID entirely in tests, instead relying on confusing SynthID decoders that try to read watermarked images.

The process used to crack the underlying mechanics of Google’s watermark is technically complex for non-developers. You can read the full breakdown on Aloshdenny’s Medium page (which was apparently written up while Aloshdenny was “high”) if you’re curious, but here’s a simplified explainer: