Proof of Capture: Apple Reference Image, but open source and using steganography

Researchers built an open-source "proof of capture" camera using a Raspberry Pi and cryptographic chip that proves photos were taken by a camera rather than AI-generated, embedding an invisible watermark in image pixels that survives compression and editing. Apple introduced a similar feature called Apple Reference Image that cryptographically signs photos at capture time, though it stores the signature separately as a "digital negative" rather than embedding it in the image, and uses Apple's proprietary system instead of the open C2PA standard already adopted by camera manufacturers and Adobe.