tmpl = tmpl.Funcs(map[string]interface{}{
        "image":                   func() string { return "%[1]s" },
        "image_slug":              func() string { return "%[2]s" },
        "image_safe_slug":         func() string { return "%[3]s" },
        "image_content_based_tag": func() string { return "%[4]s" },