It’s very easy action – just use command docker save
For example: docker save –output alpine.tar alpine:3.8
where alpine.tar – name for tar archive, alpine:3.8 – docker image name
In result, you have tar archive that can be easy to send over Dropbox, Google Cloud, email or etc.
For restore you can use command:
docker load -i alpine.tar – restore with multiple layers (if exists) or use