tumble/layouts/partials/image.html

<figure>
  <a href="{{ .Permalink | relURL }}">
    <img src="{{ relURL "/images/" }}{{ .Params.image_filename }}" alt="{{ .Params.title }}">
  </a>
  {{ if .Params.show_title  }}
    {{ with .Params.title }}<figcaption>{{ . }}</figcaption>{{ end }}
  {{ end }}
</figure>