gistfile1.rb

Cloudinary::Migrator.new(
  db_file: "tmp/cloudinary_resource_images.db",
  threads: 1,
  retrieve: ->(id) {
    resource = Resource.find(id)
    if (resource.size || resource.image.size) > 19.megabytes
      file = open(resource.image.url)
      `convert #{file.path} -quality 85 jpg:-`
    else
      resource.url
    end
  },
  # ...