---
license: apache-2.0
library_name: diffusers
pipeline_tag: unconditional-image-generation
tags:
- diffusers
- w-flow
- image-generation
- class-conditional
- one-step
- imagenet
widget:
- text: golden retriever
  output:
    url: demo.png
language:
- en
---

# W-Flow-diffusers

Native [diffusers](https://github.com/huggingface/diffusers) checkpoints for **W-Flow** ([One-Step Generative Modeling via Wasserstein Gradient Flows](https://arxiv.org/abs/2605.11755)). Code: [hanjq17/W-Flow](https://github.com/hanjq17/W-Flow). Each variant folder is self-contained:

- `pipeline.py` — `WFlowPipeline`
- `scheduler/scheduling_wflow.py` — `WFlowScheduler` (one evaluation; the transformer predicts the clean latent)
- `transformer/transformer_wflow.py` — `WFlowTransformer2DModel`
- `vae/` — `stabilityai/sd-vae-ft-mse` (`AutoencoderKL`, scaling factor 0.18215)

Load with PyPI `diffusers` and `trust_remote_code=True`. No extra W-Flow package is required. Sampling is one forward pass at 256×256. `guidance_scale` is the official CFG value, which the paper writes as \(w+1\). Weights are the released EMA. The paper reports ImageNet-256 FID 1.52 for W-Flow-B, 1.35 for W-Flow-L, and 1.29 for W-Flow-XL.

## Available checkpoints

| Checkpoint | Path | Resolution | Steps | Guidance |
| --- | --- | --- | ---: | ---: |
| W-Flow-B | [`W-Flow-B/`](W-Flow-B/) | 256×256 | 1 | 1.19 |
| W-Flow-L | [`W-Flow-L/`](W-Flow-L/) | 256×256 | 1 | 1.14 |
| W-Flow-XL | [`W-Flow-XL/`](W-Flow-XL/) | 256×256 | 1 | 1.09 |

## Demo

![W-Flow-B demo](demo.png)

Class: *golden retriever* (ImageNet 207) — 256×256, 1 step, `guidance_scale=1.19`, `torch_dtype=bfloat16`, seed 1.

## ImageNet class labels

Each variant keeps an English `id2label` map in `model_index.json`.

- `pipe.id2label` — id → English label
- `pipe.labels` — synonym → id
- `pipe.get_label_ids("golden retriever")`
- `pipe(class_labels="golden retriever", ...)` — string labels resolve automatically

`height` and `width` default to 256. The patch embedding is fixed to a 32×32 latent, so other sizes are rejected. On CUDA the generator autocasts to bfloat16.

## Inference

```python
import torch
from diffusers import DiffusionPipeline

pipe = DiffusionPipeline.from_pretrained(
    "BiliSakura/W-Flow-diffusers",
    subfolder="W-Flow-B",
    custom_pipeline="pipeline.py",
    trust_remote_code=True,
    torch_dtype=torch.bfloat16,
).to("cuda")

print(pipe.id2label[207])
image = pipe(
    class_labels="golden retriever",
    num_inference_steps=1,
    guidance_scale=1.19,
    generator=torch.Generator(device="cuda").manual_seed(1),
).images[0]
image.save("demo.png")
```

Local checkout:

```python
from pathlib import Path
import torch
from diffusers import DiffusionPipeline

model_dir = Path("W-Flow-diffusers/W-Flow-B")
pipe = DiffusionPipeline.from_pretrained(
    str(model_dir),
    local_files_only=True,
    custom_pipeline=str(model_dir / "pipeline.py"),
    trust_remote_code=True,
    torch_dtype=torch.bfloat16,
).to("cuda")
```

## Citation

```bibtex
@article{han2026one,
  title   = {One-Step Generative Modeling via Wasserstein Gradient Flows},
  author  = {Han, Jiaqi and Li, Puheng and Guo, Qiushan and Xu, Renyuan and Ermon, Stefano and Cand{\`e}s, Emmanuel J.},
  journal = {arXiv preprint arXiv:2605.11755},
  year    = {2026},
  url     = {https://arxiv.org/abs/2605.11755}
}
```