Files
flux2/docs/flux2_dev_hf.md
apolinário c7a09571ba Update 4-bit text-encoder and 4-bit DiT on diffusers script for initial CPU loading (#12)
* Update diffusers script for initial CPU loading

* remove transformer
2025-11-28 11:28:31 -08:00

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7.9 KiB
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# 🧨 Running the model with diffusers
## Getting started
Install diffusers from `main` and upgrade your `transformers`, `accelerate` and `bitsandbytes` dependencies to latest
```sh
pip install git+https://github.com/huggingface/diffusers.git
pip install --upgrade transformers accelerate bitsandbytes
```
After accepting the gating on the [FLUX.2-dev repository](https://huggingface.co/black-forest-labs/FLUX.2-dev), login with Hugging Face on your terminal
```sh
hf auth login
```
See below for inference instructions on different GPUs.
---
## 💾 Lower VRAM (~24-32G) - RTX 4090 and 5090
Those with 24-32GB of VRAM can use the model with **4-bit quantization**
### 4-bit transformer and remote text-encoder (~18G of VRAM)
The diffusers team is introducing a remote text-encoder for this release.
The text-embeddings are calculated in bf16 in the cloud and you only load the transformer into VRAM (this setting can get as low as ~18G of VRAM)
```py
import torch
from diffusers import Flux2Pipeline
from diffusers.utils import load_image
from huggingface_hub import get_token
import requests
import io
repo_id = "diffusers/FLUX.2-dev-bnb-4bit" #quantized text-encoder and DiT. VAE still in bf16
device = "cuda:0"
torch_dtype = torch.bfloat16
def remote_text_encoder(prompts):
response = requests.post(
"https://remote-text-encoder-flux-2.huggingface.co/predict",
json={"prompt": prompts},
headers={
"Authorization": f"Bearer {get_token()}",
"Content-Type": "application/json"
}
)
prompt_embeds = torch.load(io.BytesIO(response.content))
return prompt_embeds.to(device)
pipe = Flux2Pipeline.from_pretrained(
repo_id, text_encoder=None, torch_dtype=torch_dtype
).to(device)
prompt = "Realistic macro photograph of a hermit crab using a soda can as its shell, partially emerging from the can, captured with sharp detail and natural colors, on a sunlit beach with soft shadows and a shallow depth of field, with blurred ocean waves in the background. The can has the text `BFL Diffusers` on it and it has a color gradient that start with #FF5733 at the top and transitions to #33FF57 at the bottom."
#cat_image = load_image("https://huggingface.co/spaces/zerogpu-aoti/FLUX.1-Kontext-Dev-fp8-dynamic/resolve/main/cat.png")
image = pipe(
prompt_embeds=remote_text_encoder(prompt),
#image=[cat_image] #optional multi-image input
generator=torch.Generator(device=device).manual_seed(42),
num_inference_steps=50, #28 steps can be a good trade-off
guidance_scale=4,
).images[0]
image.save("flux2_output.png")
```
### 4-bit transformer and 4-bit text-encoder (~20G of VRAM)
Load both the text-encoder and the transformer in 4-bit.
The text-encoder is offloaded from VRAM for the transformer to run with `pipe.enable_model_cpu_offload()`, making sure both will fit.
```py
import torch
from diffusers import Flux2Pipeline, AutoModel
from transformers import Mistral3ForConditionalGeneration
from diffusers.utils import load_image
repo_id = "diffusers/FLUX.2-dev-bnb-4bit" #quantized text-encoder and DiT. VAE still in bf16
device = "cuda:0"
torch_dtype = torch.bfloat16
text_encoder = Mistral3ForConditionalGeneration.from_pretrained(
repo_id, subfolder="text_encoder", torch_dtype=torch.bfloat16, device_map="cpu"
)
dit = AutoModel.from_pretrained(
repo_id, subfolder="transformer", torch_dtype=torch.bfloat16, device_map="cpu"
)
pipe = Flux2Pipeline.from_pretrained(
repo_id, text_encoder=text_encoder, transformer=dit, torch_dtype=torch_dtype
)
pipe.enable_model_cpu_offload()
prompt = "Realistic macro photograph of a hermit crab using a soda can as its shell, partially emerging from the can, captured with sharp detail and natural colors, on a sunlit beach with soft shadows and a shallow depth of field, with blurred ocean waves in the background. The can has the text `BFL + Diffusers` on it and it has a color gradient that start with #FF5733 at the top and transitions to #33FF57 at the bottom."
#cat_image = load_image("https://huggingface.co/spaces/zerogpu-aoti/FLUX.1-Kontext-Dev-fp8-dynamic/resolve/main/cat.png")
image = pipe(
prompt=prompt,
#image=[cat_image] #multi-image input
generator=torch.Generator(device=device).manual_seed(42),
num_inference_steps=50,
guidance_scale=4,
).images[0]
image.save("flux2_output.png")
```
To understand how different quantizations affect the model's abilities and quality, access the [FLUX.2 on diffusers](https://huggingface.co/blog/flux2) blog
---
## 💿 More VRAM (80G+)
Even an H100 can't hold the text-encoder, transormer and VAE at the same time. However, as they each fit individually, it is a matter of activating the `pipe.enable_model_cpu_offload()`
For H200, B200 or larger cards, everything fits.
```py
import torch
from diffusers import Flux2Pipeline
from diffusers.utils import load_image
repo_id = "black-forest-labs/FLUX.2-dev"
device = "cuda:0"
torch_dtype = torch.bfloat16
pipe = Flux2Pipeline.from_pretrained(
repo_id, torch_dtype=torch_dtype
)
pipe.enable_model_cpu_offload() #no need to do cpu offload for >80G VRAM carts like H200, B200, etc. and do a `pipe.to(device)` instead
prompt = "Realistic macro photograph of a hermit crab using a soda can as its shell, partially emerging from the can, captured with sharp detail and natural colors, on a sunlit beach with soft shadows and a shallow depth of field, with blurred ocean waves in the background. The can has the text `BFL Diffusers` on it and it has a color gradient that start with #FF5733 at the top and transitions to #33FF57 at the bottom."
#cat_image = load_image("https://huggingface.co/spaces/zerogpu-aoti/FLUX.1-Kontext-Dev-fp8-dynamic/resolve/main/cat.png")
image = pipe(
prompt=prompt,
#image=[cat_image] #multi-image input
generator=torch.Generator(device=device).manual_seed(42),
num_inference_steps=50,
guidance_scale=4,
).images[0]
image.save("flux2_output.png")
```
### Remote text-encoder + H100
`pipe.enable_model_cpu_offload()` slows you down a bit. You can move as fast as possible on the H100 with the remote text-encoder
```py
import torch
from diffusers import Flux2Pipeline
from diffusers.utils import load_image
from huggingface_hub import get_token
import requests
import io
repo_id = "black-forest-labs/FLUX.2-dev"
device = "cuda:0"
torch_dtype = torch.bfloat16
def remote_text_encoder(prompts):
response = requests.post(
"https://remote-text-encoder-flux-2.huggingface.co/predict",
json={"prompt": prompts},
headers={
"Authorization": f"Bearer {get_token()}",
"Content-Type": "application/json"
}
)
assert response.status_code == 200, f"{response.status_code=}"
prompt_embeds = torch.load(io.BytesIO(response.content))
return prompt_embeds.to(device)
pipe = Flux2Pipeline.from_pretrained(
repo_id, text_encoder=None, torch_dtype=torch_dtype
).to(device)
prompt = "Realistic macro photograph of a hermit crab using a soda can as its shell, partially emerging from the can, captured with sharp detail and natural colors, on a sunlit beach with soft shadows and a shallow depth of field, with blurred ocean waves in the background. The can has the text `BFL + Diffusers` on it and it has a color gradient that start with #FF5733 at the top and transitions to #33FF57 at the bottom."
#cat_image = load_image("https://huggingface.co/spaces/zerogpu-aoti/FLUX.1-Kontext-Dev-fp8-dynamic/resolve/main/cat.png")
image = pipe(
prompt_embeds=remote_text_encoder(prompt),
#image=[cat_image] #optional multi-image input
generator=torch.Generator(device=device).manual_seed(42),
num_inference_steps=50,
guidance_scale=4,
).images[0]
image.save("flux2_output.png")
```
## 🧮 Other VRAM sizes
If you have different GPU sizes, you can experiment with different quantizations, for example, for 40-48G VRAM GPUs, (8-bit) quantization instead of 4-bit can be a good trade-off. You can learn more on the [diffusers FLUX.2 release blog](https://huggingface.co/blog/flux2)