stable-diffusion.cpp/docs/sefi_image.md

How to Use

SeFi-Image uses a Flux2-style dual-time transformer (semantic + texture streams), the standard Flux2 VAE, and Qwen3-VL as the LLM text encoder. Tech report: arXiv:2606.22568.

Download weights

The SeFi-Image family ships in three scales (1B / 2B / 5B) and three families (Base / RL / turbo), all gated on Hugging Face under https://huggingface.co/SeFi-Image.

• 1B and 2B variants pair with Qwen3-VL-2B-Instruct.
• 5B variants pair with Qwen3-VL-4B-Instruct.
• All variants use the standard Flux2 VAE (flux2_ae.safetensors from https://huggingface.co/black-forest-labs/FLUX.2-dev).

Convert the transformer and text encoder to sd.cpp safetensors:

python3 script/convert_sefi.py     <hf_repo_dir>                          <out_dir>/sefi_<scale>_<family>.safetensors
python3 script/convert_qwen3_vl.py  <hf_repo_dir>/Qwen3-VL-XB-Instruct    <out_dir>/qwen3_vl_<X>b.safetensors

Variant defaults

Family	timestep_shift_alpha	steps	cfg-scale
Base	0.3	50	4.0
RL	0.3	50	4.0
turbo	1.0	4	1.0

The dispatcher picks alpha from the filename (turbo substring => 1.0, otherwise 0.3). Override via --extra-sample-args sefi_alpha=<value> or sefi_delta_t=<value>.

Examples

1B / 2B turbo

./build/bin/sd-cli --diffusion-model /path/to/sefi_1b_turbo.safetensors --vae /path/to/flux2_ae.safetensors --llm /path/to/qwen3_vl_2b.safetensors -p "a photograph of an orange tabby cat sitting on a couch" --cfg-scale 1.0 --steps 4 -W 1024 -H 1024 -s 42 --diffusion-fa --offload-to-cpu -o out.png

1B / 2B base

./build/bin/sd-cli --diffusion-model /path/to/sefi_1b_base.safetensors --vae /path/to/flux2_ae.safetensors --llm /path/to/qwen3_vl_2b.safetensors -p "a photograph of an orange tabby cat sitting on a couch" --cfg-scale 4.0 --steps 50 -W 1024 -H 1024 -s 42 --diffusion-fa --offload-to-cpu -o out.png

5B (needs streaming on 12 GiB VRAM)

./build/bin/sd-cli --diffusion-model /path/to/sefi_5b_turbo.safetensors --vae /path/to/flux2_ae.safetensors --llm /path/to/qwen3_vl_4b.safetensors -p "a photograph of an orange tabby cat sitting on a couch" --cfg-scale 1.0 --steps 4 -W 1024 -H 1024 -s 42 --diffusion-fa --max-vram 8 --stream-layers --offload-to-cpu -o out.png