An open-source tool is exploiting a quirk in how Anthropic prices image tokens to cut Claude Code and Fable 5 session costs by 59 to 70 percent — turning expensive text into cheap pixels.
The tool, called pxpipe, was developed by Steven Chong and is available on GitHub. It functions as a local proxy that intercepts requests to Claude Code and renders the bulky, static parts of the conversation — system prompts, tool documentation, and older chat history — as densely packed PNG images. Recent messages and model outputs pass through as normal text.
The trick works because of a fundamental asymmetry in how Anthropic (and most AI providers) price input tokens. Text costs roughly one token per character, but images cost a fixed number of tokens based on their pixel dimensions, regardless of how much text they contain. By rendering dense content like code or JSON as an image, pxpipe packs approximately 3.1 characters into every image token.
In one documented Fable 5 session, costs dropped from US$42.21 to US$6.06 — a reduction of roughly 86 percent. Total savings across multiple sessions averaged 59 to 70 percent, according to Chong.
The tradeoff is accuracy and speed. The approach is lossy: exact strings such as hashes can come back garbled when the model reads them from an image. Processing is also slower because the model must run rendered images through its vision encoder rather than reading text directly. By default, pxpipe supports Claude Fable 5 and GPT 5.6. Fable 5 achieves 100 percent accuracy on benchmarks involving math problems with fresh random numbers. Claude Opus 4.7 and Opus 4.8 misread approximately 7 percent of rendered images and are disabled by default.
The technique is not entirely new. DeepSeek built an OCR system that processes text documents as images, achieving up to 10x compression while retaining 97 percent of information. But pxpipe applies the concept to the specific use case of AI coding assistant sessions, where system prompts and tool documentation can account for thousands of tokens that remain largely static across interactions.
If the technique gains widespread adoption, AI companies may respond by adjusting image processing pricing or introducing new pricing structures that close the arbitrage window.
Sources: Open-source tool pxpipe hides text in PNGs to cut Claude Code and Fable 5 token costs up to 70% (The Decoder, July 4, 2026); pxpipe repository (GitHub)