Contextual Vision Transformers for Robust Representation Learning
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We present Contextual Vision Transformers (ContextViT), a method for producing robust feature representations for images exhibiting grouped structure such as covariates. ContextViT introduces an extra context token to encode group-specific information, allowing the model to explain away group-specific covariate structures while keeping core visual features shared across groups. Specifically, given an input image, Context-ViT maps images that share the same covariate into this context token appended to the input image tokens to capture the effects of conditioning the model on group membership. We furthermore introduce a context inference network to predict such tokens on the fly given a few samples from a group distribution, enabling ContextViT to generalize to new testing distributions at inference time. We illustrate the performance of ContextViT through a diverse range of applications. In supervised fine-tuning, we demonstrate that augmenting pre-trained ViTs with additional context conditioning leads to significant improvements in out-of-distribution generalization on iWildCam and FMoW. We also explored self-supervised representation learning with ContextViT. Our experiments on the Camelyon17 pathology imaging benchmark and the cpg-0000 microscopy imaging benchmark demonstrate that ContextViT excels in learning stable image featurizations amidst covariate shift, consistently outperforming its ViT counterpart.
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