“How does Fable 5.1 hide messages in images?” by Nikita Kezin, 13ryanC, hronir, James Chua

LessWrong (30+ Karma) · Oct 22, 2026 · 13m

TL;DR

Frontier LLMs are now capable of generating artistic images using SVG. We ask – if these LLMs had to hide a message in an image – how would they do so? And if they hid such messages, could they be successfully decoded?

We show interesting results from testing Fable 5.1 on these questions, and briefly compare with GPT-6 Astra on the same task.

Figure 1: The stars encode a message, read left to right. Each star's height represents its place in the alphabet. Hidden message: The monster acts on the moonshine module.

Introduction

Frontier LLMs can now capably generate images. Whenever asked…