OrCo: Towards Better Generalization via Orthogonality and Contrast for Few-Shot Class-Incremental Learning
Authors: Noor Ahmed, Anna Kukleva, Bernt Schiele

Few-Shot Class-Incremental Learning (FSCIL) introduces a paradigm in which the problem space expands with limited data. FSCIL methods inherently face the challenge of catastrophic forgetting as data arrives incrementally making models susceptible to overwriting previously acquired knowledge. Moreover given the scarcity of labeled samples available at any given time models may be prone to overfitting and find it challenging to strike a balance between extensive pretraining and the limited incremental data. To address these challenges we propose the OrCo framework built on two core principles: features' orthogonality in the representation space and contrastive learning. In particular we improve the generalization of the embedding space by employing a combination of supervised and self-supervised contrastive losses during the pretraining phase. Additionally we introduce OrCo loss to address challenges arising from data limitations during incremental sessions. Through feature space perturbations and orthogonality between classes the OrCo loss maximizes margins and reserves space for the following incremental data. This in turn ensures the accommodation of incoming classes in the feature space without compromising previously acquired knowledge. Our experimental results showcase state-of-the-art performance across three benchmark datasets including mini-ImageNet CIFAR100 and CUB datasets. Code is available at https://github.com/noorahmedds/OrCo