Is it Albert Einstein ... or Marilyn Monroe?
It depends on how far back from this graphic you stand ...
And that's the optional part. Up close, Albert. Stand back a few feet ... Marilyn.
While I have no frigg'n idea how they did it, one suspects it's the same property of human eyesight that makes a big funny mosaic of pixels become a detailed, delicately-shaded desktop icon when viewed at size.
Also can't figure out where it's come from. But it's all over the intarmets.