Betran Russell's Celestial Teapot can be used to counter the argument: "The absence of proof is not a proof of absence". Indeed - the absence of proof actually is a proof of absence.
So, if you stare at the picture you may eventually see a 3D teapot. The teapot you may see is not celestial.
An interesting question is: Where is the teapot that you (may) see?
In this particular case the optic center of the brain is not making up the teapot but instead the teapot is carefully inserted into the seemingly random set of pixels that make up the picture and the optic center of the brain somehow, eventually teases out the image from the apparent random set of pixels. The image is called and Autosterogram.