The Uncanny is difficult to define and very difficult to categorise, it's a word that is unrelated to anything else, "Canny" comes from a translation of a German word unheimlich which has the clear meaning of 'homely' suggesting that something uncanny is something unhomely. Weird pictures are often surreal but not necessarily uncanny, they are relatively straight forward images.
The exhibition "Dead Dad" by Ron Mueck has an uncanny effect in the change in scale, the image looks normal yet the model is only tiny. The uncanny is disturbing rather than surprising and this is a perfect example of something that is disturbing. The change in scale is something that creeps up on you slowly.
For an uncanny effect we can distinguish something strange about something familiar, and something strange added to something familiar. Uncanny likeness is a likeness that is strange, but not complete, complete likeness would be identity rather than likeness. Identical twins are an interesting case of the uncanny, we are used to thinking that people are unique, so it is unsettling to see twins. The 'double' is an element in the uncanny according to Freud, the closer the resemblance, the more we see the difference. An example of this would be the twins in the shining, or Diane Arbus identical twins.
Masahiro Mori, the uncanny valley (1970) this idea is concerned with the question of likeness or resemblance, the realism drops away when you get to certain characters. Cuba girl for example is a robot, if you look up this diagram you will find more examples, one of which deals with 2D images and one with 3D, also one with animated and static. Cuba girl is a good example because when she is still, she looks quite realistic and it is only when she starts to move that you get a weird uncanny effect.
A real person doesn't represent the goal of realism but is the model of realism as you wouldn't say "God you look really real". It could be argued that the grey panel is the uncanny. It's when characters get very close together that it becomes uncanny because there is a gap between the two.
Freud believes that the question of likeness isn't very interesting and to not the real meaning of the uncanny, he thinks it's more about repressing a disturbing memory through retreated behaviour. He agrees with Schelling who said the uncanny is everything which should remain mysterious, hidden, latent and has come to light. Both would probably agree that the work of Louise Bourgeois is a good example of the uncanny. The distinction between what is the uncanny and what is not has a very fine line and it is the ways in which the image is interpreted that can distinguish this.