Fingerprinting image assets with pure markdown templates?

Uh? There’s an example of render-image.html being used. You would only need to pipe the .Destination. Something like:

{{ $title := .Title }}
{{ $altTxt := .Text }}

{{ with resources.GetMatch .Destination }}
  <img src="{{ (. | fingerprint).Permalink }}" alt="{{ $altTxt }}" {{ with $title }} title="{{ . }}"{{ end }} />
{{ end }}

Can’t really give you an exact answer since I don’t know your project structure.

In this example, ![Some image.](img/some-image.jpg) is picking the assets/img/some-image.jpg, processing and rendering the image file with the fingerprint.