One speaks of optical illusions, visual perception, if not correspond to reality, as they could be objectively measured. Our perception is always subjective, as the information of the senses are affected by the brain. In general, helps us greatly, because we can respond faster, because our brain for example, experience in the interpretation of perceptions into account. But this can be exploited to design and target images, and models where this system is not working. These illusions can naturally occur in nature, where they are rare. This type of perceptual illusions caused by the communication between the eyes and brain, are called optical illusions. Most people are aware of optical illusions, which most do not know how they work. In summary one can say that the emergence of visual illusions by the interplay of visual perception and the brain. But there are many different types of delusions. When we compare the size illusions unknowinglythe size of various objects and then draw conclusions about the different sizes. Exactly, this process allows us to then make a false assumption. The same principle is also at Farbtuschungen and brightness illusion, is compared to the size where only the color or brightness of objects. But there are many other optical illusions. Examples are motion illusions, which is produced in a static image of the impression of a dynamic, or Kippfigur that allow for their different interpretations of ambiguous content. Even in everyday life we often encounter optical illusions, such as rainbows, sun and moon illusions deformations. There are also some artists who deal with visual illusions. Among the most famous painters probably belongs MC Escher.