can’t pull graphdb-workbench docker image

docker run -d -p 8080:80 -e GRAPHDB_URL=127.0.0.1:7200 graphdb-workbench
Unable to find image ‘graphdb-workbench:latest’ locally
docker: Error response from daemon: pull access denied for graphdb-workbench, repository does not exist or may require ‘docker login’: denied: requested access to the resource is denied.

Source: Docker Questions