Microsoft Paint Apps Secretly Watermark AI-Generated Images

Microsoft's Paint and Photos apps have been found to embed an invisible watermark in AI-generated content. Developer Xusheng Li discovered this feature while investigating the apps' AI capabilities. The watermark is a GUID (Globally Unique Identifier) that is mixed into the pixels of the image, making it undetectable to the human eye.

The watermarking process uses a server-issued GUID and attaches C2PA (Coalition for Content Provenance and Authenticity) credentials to the saved file. This means that even if local image generation occurs on a device, the prompt is still sent to Microsoft servers for moderation. If the watermarking process fails, Paint will abort the entire image generation process.

The reason behind this mandatory watermarking is likely related to Article 50 of the EU AI Act, which requires AI-generated content to carry a detectable, machine-readable mark by August 2, 2026.