Just take the default-plugin and remove the text:
Either change the file default.html
in the template-folder or add a new file to the template-folder. File-content:
<a href="{{full_image_url}}" title="{{image_title}}" alt="{{image_title}}" {{#window_image}}target="_blank" {{/window_image}}>
{{#size}}{{{image}}}{{/size}}{{^size}}{{{thumbnail}}}{{/size}}
</a>
You could also add the template directly in the shortcode:
[random_image_template]<a href="{{full_image_url}}" title="{{image_title}}">
{{#size}}{{{image}}}{{/size}}{{^size}}{{{thumbnail}}}{{/size}}
</a>[/random_image_template]