swinv2.md

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*This model was released on 2021-11-18 and added to Hugging Face Transformers on 2022-07-27.*

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# Swin Transformer V2

[Swin Transformer V2](https://huggingface.co/papers/2111.09883) is a 3B parameter model that focuses on how to scale a vision model to billions of parameters. It introduces techniques like residual-post-norm combined with cosine attention for improved training stability, log-spaced continuous position bias to better handle varying image resolutions between pre-training and fine-tuning, and a new pre-training method (SimMIM) to reduce the need for large amounts of labeled data. These improvements enable efficiently training very large models (up to 3 billion parameters) capable of processing high-resolution images.

You can find official Swin Transformer V2 checkpoints under the [Microsoft](https://huggingface.co/microsoft?search_models=swinv2) organization.

> [!TIP]
> Click on the Swin Transformer V2 models in the right sidebar for more examples of how to apply Swin Transformer V2 to vision tasks.

<hfoptions id="usage">
<hfoption id="Pipeline">

```py
import torch
from transformers import pipeline

pipeline = pipeline(
    task="image-classification",
    model="microsoft/swinv2-tiny-patch4-window8-256",
    dtype=torch.float16,
    device=0
)
pipeline("https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg")
```

</hfoption>

<hfoption id="AutoModel">

```py
import torch
import requests
from PIL import Image
from transformers import AutoModelForImageClassification, AutoImageProcessor

image_processor = AutoImageProcessor.from_pretrained(
    "microsoft/swinv2-tiny-patch4-window8-256",
)
model = AutoModelForImageClassification.from_pretrained(
    "microsoft/swinv2-tiny-patch4-window8-256",
    device_map="auto"
)

url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"
image = Image.open(requests.get(url, stream=True).raw)
inputs = image_processor(image, return_tensors="pt").to(model.device)

with torch.no_grad():
  logits = model(**inputs).logits

predicted_class_id = logits.argmax(dim=-1).item()
predicted_class_label = model.config.id2label[predicted_class_id]
print(f"The predicted class label is: {predicted_class_label}")
```

</hfoption>
</hfoptions>

## Notes

- Swin Transformer V2 can pad the inputs for any input height and width divisible by `32`.
- Swin Transformer V2 can be used as a [backbone](../backbones). When `output_hidden_states = True`, it outputs both `hidden_states` and `reshaped_hidden_states`. The `reshaped_hidden_states` have a shape of `(batch, num_channels, height, width)` rather than `(batch_size, sequence_length, num_channels)`.

## Swinv2Config

[[autodoc]] Swinv2Config

## Swinv2Model

[[autodoc]] Swinv2Model
    - forward

## Swinv2ForMaskedImageModeling

[[autodoc]] Swinv2ForMaskedImageModeling
    - forward

## Swinv2ForImageClassification

[[autodoc]] transformers.Swinv2ForImageClassification
    - forward