Abstract: The present disclosure provides a domain generalization method, device, server, and client. The method includes acquiring image discrimination information uploaded from multiple clients, wherein the image discrimination information is obtained by discriminators in the clients, the discriminators evaluating enhanced image generated by a generator in the server based on initial image of the respective clients, the initial image including amplitude information; and updating the generator based on the image discrimination information to obtain an updated generator; sending a multi-domain mixed image generated by the updated generator to the clients; and determining domain generalization parameters for classifiers in each client, based on model update parameters obtained after the clients update their classifiers using the initial image and the multi-domain mixed image.