docker/docker_transport.go
func ParseReference(refString string) (types.ImageReference, error) {
	if !strings.HasPrefix(refString, "//") {
		return nil, errors.Errorf("docker: image reference %s does not start with //", refString)
	}
	ref, err := reference.ParseNormalizedNamed(strings.TrimPrefix(refString, "//"))
	if err != nil {
		return nil, err
	}
	ref = reference.TagNameOnly(ref)
	return NewReference(ref)
}
func ParseReference(refString string) (types.ImageReference, error) {
	if !strings.HasPrefix(refString, "//") {
		return nil, errors.Errorf("docker: image reference %s does not start with //", refString)
	}
	ref, err := reference.ParseNormalizedNamed(strings.TrimPrefix(refString, "//"))
	if err != nil {
		return nil, err
	}
	ref = reference.TagNameOnly(ref)
	return NewReference(ref)
}
// ParseReference converts a string, which should not start with the ImageTransport.Name prefix, into an Docker ImageReference.