A fast, powerful, and simple hierarchical vision transformer
Project description
Hiera: A Hierarchical Vision Transformer without the Bells-and-Whistles
This is the official implementation for our ICML 2023 Oral paper:
Hiera: A Hierarchical Vision Transformer without the Bells-and-Whistles
Chaitanya Ryali*,
Yuan-Ting Hu*,
Daniel Bolya*,
Chen Wei,
Haoqi Fan,
Po-Yao Huang,
Vaibhav Aggarwal,
Arkabandhu Chowdhury,
Omid Poursaeed,
Judy Hoffman,
Jitendra Malik,
Yanghao Li*,
Christoph Feichtenhofer*
ICML '23 Oral | GitHub | arXiv | BibTeX
*: Equal contribution.
What is Hiera?
Hiera is a hierarchical vision transformer that is fast, powerful, and, above all, simple. It outperforms the state-of-the-art across a wide array of image and video tasks while being much faster.
How does it work?
Vision transformers like ViT use the same spatial resolution and number of features throughout the whole network. But this is inefficient: the early layers don't need that many features, and the later layers don't need that much spatial resolution. Prior hierarchical models like ResNet accounted for this by using fewer features at the start and less spatial resolution at the end.
Several domain specific vision transformers have been introduced that employ this hierarchical design, such as Swin or MViT. But in the pursuit of state-of-the-art results using fully supervised training on ImageNet-1K, these models have become more and more complicated as they add specialized modules to make up for spatial biases that ViTs lack. While these changes produce effective models with attractive FLOP counts, under the hood the added complexity makes these models slower overall.
We show that a lot of this bulk is actually unnecessary. Instead of manually adding spatial bases through architectural changes, we opt to teach the model these biases instead. By training with MAE, we can simplify or remove all of these bulky modules in existing transformers and increase accuracy in the process. The result is Hiera, an extremely efficient and simple architecture that outperforms the state-of-the-art in several image and video recognition tasks.
News
- [2023.06.01] Initial release.
Installation
Hiera requires a reasonably recent version of torch. After that, you can install hiera through pip:
pip install hiera-transformer
This repo should support the latest timm version, but timm is a constantly updating package. Create an issue if you have problems with a newer version of timm.
Installing from Source
If using torch hub, you don't need to install the hiera
package. But, if you'd like to develop using hiera, it could be a good idea to install it from source:
git clone https://github.com/facebookresearch/hiera.git
cd hiera
python setup.by build develop
Model Zoo
Here we provide model checkpoints for Hiera. Each model listed is accessible on torch hub, e.g.:
model = torch.hub.load("facebookresearch/hiera", model="hiera_base_224")
The model name is the same as the checkpoint name.
Note: the speeds listed here were benchmarked without PyTorch's optimized scaled dot product attention. If using PyTorch 2.0 or above, your inference speed will probably be faster than what's listed here.
Coming Soon
As of now, base finetuned models are available. The rest are coming soon.
Image Models
Model | Input Size | Pretrained Models (IN-1K MAE) |
Finetuned Models (IN-1K Supervised) |
IN-1K Top-1 (%) |
A100 fp16 Speed (im/s) |
---|---|---|---|---|---|
Hiera-T | 224x224 | mae_hiera_tiny_224 | hiera_tiny_224 | 82.8 | 2758 |
Hiera-S | 224x224 | mae_hiera_small_224 | hiera_small_224 | 83.8 | 2211 |
Hiera-B | 224x224 | mae_hiera_base_224 | hiera_base_224 | 84.5 | 1556 |
Hiera-B+ | 224x224 | mae_hiera_base_plus_224 | hiera_base_plus_224 | 85.2 | 1247 |
Hiera-L | 224x224 | mae_hiera_large_224 | hiera_large_224 | 86.1 | 531 |
Hiera-H | 224x224 | mae_hiera_huge_224 | hiera_huge_224 | 86.9 | 274 |
Video Models
Model | Input Size | Pretrained Models (K400 MAE) |
Finetuned Models (K400) |
K400 (3x5 views) Top-1 (%) |
A100 fp16 Speed (clip/s) |
---|---|---|---|---|---|
Hiera-B | 16x224x224 | Coming Soon | hiera_base_16x224 | 84.0 | 133.6 |
Hiera-B+ | 16x224x224 | Coming Soon | hiera_base_plus_16x224 | 85.0 | 84.1 |
Hiera-L | 16x224x224 | Coming Soon | hiera_large_16x224 | 87.3 | 40.8 |
Hiera-H | 16x224x224 | Coming Soon | hiera_huge_16x224 | 87.8 | 20.9 |
Usage
This repo implements the code to run Hiera models for inference. This repository is still in progress. Here's what we currently have available and what we have planned:
- Image Inference
- MAE implementation
- Video Inference
- MAE implementation
- Training scripts
- Full Model Zoo
See examples for examples of how to use Hiera.
Inference
See examples/inference for an example of how to prepare the data for inference.
Instantiate a model with either torch hub or by installing hiera and running:
import hiera
model = hiera.hiera_base_224(pretrained=True)
Then you can run inference like any other model:
output = model(x)
Video inference works the same way, just use a 16x224
model instead.
Note: for efficiency, Hiera re-orders its tokens at the start of the network (see the Roll
and Unroll
modules in hiera_utils.py
). Thus, tokens aren't in spatial order by default. If you'd like to use intermediate feature maps for a downstream task, pass the return_intermediates
flag when running the model:
output, intermediates = model(img_norm[None, ...], return_intermediates=True)
Benchmarking
We provide a script for easy benchmarking. See examples/benchmark to see how to use it.
Scaled Dot Product Attention
PyTorch 2.0 introduced optimized scaled dot product attention, which can speed up transformers quite a bit. We didn't use this in our original benchmarking, but since it's a free speed-up this repo will automatically use it if available. To get its benefits, make sure your torch version is 2.0 or above.
Training
Coming soon.
Citation
If you use Hiera or this code in your work, please cite:
@article{ryali2023hiera,
title={Hiera: A Hierarchical Vision Transformer without the Bells-and-Whistles},
author={Ryali, Chaitanya and Hu, Yuan-Ting and Bolya, Daniel and Wei, Chen and Fan, Haoqi and Huang, Po-Yao and Aggarwal, Vaibhav and Chowdhury, Arkabandhu and Poursaeed, Omid and Hoffman, Judy and Malik, Jitendra and Li, Yanghao and Feichtenhofer, Christoph},
journal={ICML},
year={2023}
}
License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Contributing
See contributing and the code of conduct.
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