We are going to implement importing/exporting OCI v1 images in tar format (#1013)

There has been some proposals to add more formats in the PR:

• OCI v1 images in generic directory - by @AkihiroSuda
  -- Can access oci-layout and detect the format without scanning whole the "tape"
  -- Can only import really referenced blobs without scanning whole the "tape"
  -- Can be used for NFS/IPFS/S3/whatever distribution, although it would need some extra component for controlling concurrency, update, and security (client: add Import() and Export() for importing/exporting image in OCI format #1013 (comment))

• docker save/load format (aka Docker Image Spec v1 https://github.com/moby/moby/blob/master/image/spec/v1.md) - by @stevvooe client: add Import() and Export() for importing/exporting image in OCI format #1013 (comment)

Also, we may want to add support for importing/exporting raw rootfs directory.