URL

  "image": "http://link.to/you/picture"
}

Data URI

{
  "image": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="
}

1. Update the alternative text of the image and set the {d.image} marker.
2. Add the corresponding value in the JSON data field to render the document.