  Prompt learning for vision-language models, e.g., CoOp, has shown great
success in adapting CLIP to different downstream tasks, making it a promising
solution for federated learning due to computational reasons. Existing prompt
learning techniques replace hand-crafted text prompts with learned vectors that
offer improvements on seen classes, but struggle to generalize to unseen
classes. Our work addresses this challenge by proposing Federated Text-driven
Prompt Generation (FedTPG), which learns a unified prompt generation network
across multiple remote clients in a scalable manner. The prompt generation
network is conditioned on task-related text input, thus is context-aware,
making it suitable to generalize for both seen and unseen classes. Our
comprehensive empirical evaluations on nine diverse image classification
datasets show that our method is superior to existing federated prompt learning
methods, that achieve overall better generalization on both seen and unseen
classes and is also generalizable to unseen datasets.
