How to render an image at its original size? There are plenty of examples on the internet on how to render a styled image; for instance this one from web omelette:

$render = [
    '#theme' =&gt; 'image_style',
    '#style_name' =&gt; 'thumbnail',
    '#uri' =&gt; 'public://my-image.png',
    // optional parameters
];


However I do not want to use an image style. I want to render the original untouched image. So I tried:

$render = [
    '#theme' =&gt; 'image_style',
    '#style_name' =&gt; NULL,
    '#uri' =&gt; 'public://my-image.png',
    // optional parameters
];


Which did not work. 
How do I render the original full-size image?
You can also use the #theme property image (which does not appear to be documented anywhere), but gives a valid image tag.

$render= [
  '#theme' =&gt; 'image',
  '#uri' =&gt; $file-&gt;getFileUri(),
];


Which becomes &lt;img src="/sites/default/files/image.png" alt="" /&gt; once rendered.