README.md

APLA: A Simple Adaptation Method for Vision Transformers

This repo has implementation for the following papers:

• APLA: A Simple Adaptation Method for Vision Transformers
• Efficient Self-Supervised Adaptation for Medical Image Analysis

APLA (Attention Projection Layer Adaptation) is a lightweight yet effective method for adapting Vision Transformers (ViTs). We identify the projection layer immediately following the attention mechanism as critical for adaptation. APLA tunes only this layer—or even a random subset of its weights—without modifying the architecture or adding parameters. Despite its simplicity, APLA delivers strong performance with remarkable efficiency.

APLA is a targeted adapation approach that tunes only the projection layer immediately following attention. It does not intorduce any new parameters, and leverages the existing ViT architecture for adaptation.

APLA is versatile and can easily be used for classification, segmentation and detection tasks. Further, it can seamlessly be employed for both supervised and self-supervised learning.

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Simple implementation

APLA can be easily implemented using the APLA package, which provides the implementation of APLA and helper functions to directly replace Attention module with APLA_Attention.

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Installations

Please refer to the Dockerfile and use build_docker.sh to build the image. For self-supervision with dinov2, additional installations are required. You can find the necessary packages in conda-dinov2. It is recommended to set up a separate conda environment for installing the dinov2 packages.

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Datasets

This repository implements many datasets, please refer to datasets.py for their implementation.

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Usage

This repository contains code for both supervised and self-supervised adaptation (with dinov2).

Supervised adaptation

Each parameter file follows the hierarchy similar to params/finetune/dinov2/NABirds/vit_b/apla.yml which correponds to supervsied adaptaiton on the NABirds dataset using APLA, with dinov2 initialization using the vit_b architecture.

For the APLA parameter file, the partial_size attribute refers to the APLA rank, which defines how many columns of the projection weight matrix will be tuned.

To do supervised adaptation with APLA run:

# code needs to be run from src dir
cd src
python main.py --params_path ../params/finetune/dinov2/NABirds/vit_b/apla.yml

Self-supervised adaptation

The structure follows a similar pattern as supervised adaptation. Each parameter file follows the hierarchy similar to params/pretrain/dinov2/ISIC2019/vit_b/apla.yml which correponds to self-supervsied adaptaiton on the ISIC2019 dataset using APLA, with dinov2 initialization using the vit_b architecture.

To do self-supervised adaptation with APLA using the dinov2 objective run:

# code needs to be run from src dir
cd src
python main.py --dinov2 --params_path ../params/pretrain/dinov2/ISIC2019/vit_b/apla.yml

Segmentation and Detection

Please refer to the corresponding README.

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Citation

@article{sorkhei2025apla,
  title={APLA: A Simple Adaptation Method for Vision Transformers},
  author={Sorkhei, Moein and Konuk, Emir and Smith, Kevin and Matsoukas, Christos},
  journal={arXiv preprint arXiv:2503.11335},
  year={2025}
}

@article{sorkhei2025efficient,
  title={Efficient Self-Supervised Adaptation for Medical Image Analysis},
  author={Sorkhei, Moein and Konuk, Emir and Guo, Jingyu and Matsoukas, Christos and Smith, Kevin},
  journal={arXiv preprint arXiv:2503.18873},
  year={2025}
}

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Acknowledgement

This repo is built on medical_transformers, Dinov2, Dino, and timm repositories. Thanks for their great work.