Our brains use the image formed on the retina of the eye to give us a picture of the outside world. sometimes the brain is misled and interprets the information wrongly.The we see an optical illusion. Straight lines can be made to appear curved. Two lines of the same length can be seem to be of different lengths. The eye can be misled by what else is surrounding these lines .
We often have a false impression of movement . Suppose two trains are sitting in a station. and then one starts to move. The passengers of the other train often think incorrectly, that their train is leaving the station .They were expecting to move, and when they see movement assume their train is departing.
THE LAW OF PERSPECTIVE:
As an object moves into the distance it appears to grow smaller .In the, same way the parallel lines , like the edges of a road or a railway line . give the illusion drawing together as they become further away.These things appear to us is perspective.
The picture can be seen in either of two ways. If you stare at it for long enough you will see first a candlestick. Then suddenly it will look like two faces. You will not see both candlestick and faces at the same time
Optical illusions. In figure 1 and 2 the two red lines appear to be of different lengths because of the angle of the green lines. They are actually exactly the same length.
When we watch a film the eye sees the slight changes in detail in each picture as a continuous change, which it interprets as movement.The square holes on the edges of the film guide it through the projector.
Each of your eyes is shaped like ball . Most of the ball is safely shielded inside your head. At the fron of the eye is a transparent outer layer called the cornea. The coloured part of the eye is called the iris. The middle of which appears
black. This is actually a hole , called the pupil. It automatically grows bigger or smaller to let in more or less light.
From the pupil the light passes through a lens. This can alter it shape to focus images from near or far on to the retina.
The retina is the black wall on the inside of the eye. It contains millions of light sensitive cells called rods and cones. These cells convert the light into electrical messages which are carried to the brain by the optic nerve.
Every image that is focused on the retina is upside-down. The brain automatically turns the image the right way up in our minds. Each eye sees a slightly different view of an object .Because of this we see a rounded or three dimensional viewof things.If we have one eye in the centre of our faces, objects would seem much flatter. A camera uses one lens to produce an image. This is why a photograph looks two-dimensional.
Some More Interesting Pictures on Optical Illusion:
1) Keep in mind that this is a static image. It is not animated in any way. but as your vision moves back and forth the center area seems to be moving toward the center (contracting) and the outer edges seem to be moving away (expanding) from the center. Also worth noting is that if you fixate on a point in the center and don't move your eyes this anomalous motion will stop.
2) A scintillating grid illusion. Shape, position, colour, and 3D contrast converge to produce the illusion of black dots at the intersections
4) Motion Clock : Here is an anomalous motion illusion that was created for me by Herman . If you don't see the motion, slowly move your eyes around the clock face