Eric Lu, an AI researcher and founder of Mixfont, has created an experimental font called Decoy Font. It is designed specifically to mask written text from automatic recognition systems and multimodal AI models using hybrid imaging technology. Humans only need to squint to read the font.
Eric Lu, an AI researcher and founder of Mixfont, has created an experimental font called Decoy Font. It is designed specifically to mask written text from automatic recognition systems and multimodal AI models using hybrid imaging technology. Humans only need to squint to read the font.
The developer shared his new experiment on the Mixfont project blog. He also published a ready-made font file in TTF format on the platform, which anyone can download and test in their own projects or web designs.
Decoy Font technology is based on the concept of hybrid images, a well-known method of creating optical illusions that combine high and low spatial frequencies. The developer used an original approach to build the letters: the thin and clear contours of the «decoy» are displayed in the foreground, while the real message is hidden in the background in the form of blurred symbols with a low frequency.
When a person looks at such text up close, they see only a set of decoy letters, but if they move the screen away or simply squint, the hidden word appears before their eyes. In contrast, most modern AI models, such as ChatGPT or Gemini 3.5 with Thinking, read pixels up close and focus exclusively on the clear contours of the foreground, which is why they produce a meaningless set of characters instead of real text.
The Decoy Font character design is based on the popular DejaVu Sans Mono font. However, the font file itself works in such a way that for each letter entered, the algorithm adds two more decoy letters. This process is not deterministic: an element of randomness selects a new «decoy letter» each time, which makes it impossible to simply automatically decode by pattern.
«I think it’s an interesting experiment and project that also demonstrates that artificial intelligence is not perfect,» says Eric Lu.
At the same time, the developer admits that Decoy Font does not guarantee 100% protection against recognition, as advanced AI agents with programming skills or with the help of special prompts can eventually learn to read the hidden text. However, at the initial stage, the font remains an effective tool for preventing automatic data collection (scraping).
This is not the first anti-AI experiment by the Mixfont team. Previously, the developers presented the Ghost Font project — a dynamic typography system that hides text messages in an animated video with moving dots. Unlike Ghost Font, which requires a video format to reproduce the movement, Decoy Font functions as a classic static TTF file, which allows it to be easily integrated into websites, printed posters or other graphic materials to protect the content from accidental viewing by AI bots.
