'Ghost Font' Encodes Text in Motion That Humans Read but Multimodal AI Can't

Mixfont·medium signal

Ghost Font, built by Eric Lu and the Mixfont team in San Francisco, encodes messages as colored dots rendered in the exact background color — invisible in any single frame but readable by the human motion-detecting visual system once the video plays. Because current multimodal models process video as discrete frames rather than continuous motion, the browser-based tool reportedly hides text even from top models, using decoy messages to defeat frame sampling. It hit 226 points on Hacker News and is a concrete demonstration of the frame-vs-motion architectural gap in vision models — relevant to anyone building or red-teaming multimodal pipelines.