Ability to add border or stroke to any image or video element

It seems like it would be relatively easy to have an attribute for any video or image element that allowed you to add a stroke of any color, thickness, and corner roundedness, like shapes do in Photoshop or Illustrator. This would be particularly useful for any instance of picture-in-picture type use. There are a number of inelegant workarounds for this, of course, but they're all a major pain to implement.

Thanks!