Grad-CL: Source Free Domain Adaptation with Gradient Guided Feature Disalignment

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Main Authors: Thakur, Rini Smita, Dwivedi, Rajeev Ranjan, Kurmi, Vinod K
Format: Preprint
Published: 2025
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author Thakur, Rini Smita
Dwivedi, Rajeev Ranjan
Kurmi, Vinod K
author_facet Thakur, Rini Smita
Dwivedi, Rajeev Ranjan
Kurmi, Vinod K
contents Accurate segmentation of the optic disc and cup is critical for the early diagnosis and management of ocular diseases such as glaucoma. However, segmentation models trained on one dataset often suffer significant performance degradation when applied to target data acquired under different imaging protocols or conditions. To address this challenge, we propose \textbf{Grad-CL}, a novel source-free domain adaptation framework that leverages a pre-trained source model and unlabeled target data to robustly adapt segmentation performance without requiring access to the original source data. Grad-CL combines a gradient-guided pseudolabel refinement module with a cosine similarity-based contrastive learning strategy. In the first stage, salient class-specific features are extracted via a gradient-based mechanism, enabling more accurate uncertainty quantification and robust prototype estimation for refining noisy pseudolabels. In the second stage, a contrastive loss based on cosine similarity is employed to explicitly enforce inter-class separability between the gradient-informed features of the optic cup and disc. Extensive experiments on challenging cross-domain fundus imaging datasets demonstrate that Grad-CL outperforms state-of-the-art unsupervised and source-free domain adaptation methods, achieving superior segmentation accuracy and improved boundary delineation. Project and code are available at https://visdomlab.github.io/GCL/.
format Preprint
id arxiv_https___arxiv_org_abs_2509_10134
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Grad-CL: Source Free Domain Adaptation with Gradient Guided Feature Disalignment
Thakur, Rini Smita
Dwivedi, Rajeev Ranjan
Kurmi, Vinod K
Computer Vision and Pattern Recognition
Accurate segmentation of the optic disc and cup is critical for the early diagnosis and management of ocular diseases such as glaucoma. However, segmentation models trained on one dataset often suffer significant performance degradation when applied to target data acquired under different imaging protocols or conditions. To address this challenge, we propose \textbf{Grad-CL}, a novel source-free domain adaptation framework that leverages a pre-trained source model and unlabeled target data to robustly adapt segmentation performance without requiring access to the original source data. Grad-CL combines a gradient-guided pseudolabel refinement module with a cosine similarity-based contrastive learning strategy. In the first stage, salient class-specific features are extracted via a gradient-based mechanism, enabling more accurate uncertainty quantification and robust prototype estimation for refining noisy pseudolabels. In the second stage, a contrastive loss based on cosine similarity is employed to explicitly enforce inter-class separability between the gradient-informed features of the optic cup and disc. Extensive experiments on challenging cross-domain fundus imaging datasets demonstrate that Grad-CL outperforms state-of-the-art unsupervised and source-free domain adaptation methods, achieving superior segmentation accuracy and improved boundary delineation. Project and code are available at https://visdomlab.github.io/GCL/.
title Grad-CL: Source Free Domain Adaptation with Gradient Guided Feature Disalignment
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2509.10134