Black Forest Labs releases FLUX 3 Image Klein Prompt Upsampler, a 9B model for image prompts

Black Forest Labs releases FLUX 3 Image Klein Prompt Upsampler, a 9B vision-language model fine-tuned from Qwen3.5-9B that expands short image requests into detailed prompts for the FLUX 3 Image Klein image model.

The model accepts up to 10 reference images and optional bounding boxes, and is released on Hugging Face under the Apache License 2.0. It is on by default in the FLUX 3 inference code, and its output is English.