cupper-hugo-theme/layouts/shortcodes/figure.html

{{ $original := .Page.Resources.GetMatch (printf "*%s*" (.Get "img")) }}
{{ $new := "" }}

{{ if eq (.Get "command") "Fit" }}
  {{ $new = $original.Fit (.Get "options") }}
{{ else if eq (.Get "command") "Fill" }}
  {{ $new = $original.Fill (.Get "options") }}
{{ else if eq (.Get "command") "Resize" }}
  {{ $new = $original.Resize (.Get "options") }}
{{ else if eq (.Get "command") "Original" }}
  {{ $new = $original }}
{{ else }}
  {{ errorf "Invalid image processing command: Must be one of Fit, Fill, Resize, Original." }}
{{ end }}

<figure role="group" aria-describedby="caption-{{ (.Get "caption") | md5 }}">
  <a href="{{ $original.Permalink }}" class="img-link">
    <img src="{{ $new.Permalink }}">
  </a>
  <figcaption id="caption-{{ (.Get "caption") | md5 }}">
    {{ (.Get "caption") | markdownify }}
  </figcaption>
</figure>