In some scenarios when you don't have access to the Docker registry, or limited or no internet, then this approach can be hepful.
Save image as a tar archive
docker save -o docker-image.tar <image name or ID>Once you have the tar archive, move it to another machine (on USB, over ssh), and there execute
docker load -i docker-image.tar
docker images | grep <image ID>
docker tag <image ID> <image name:image tag>