Optical Illusions Objective: To know why optical illusions occur.

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What is an Optical Illusion?

• Much of what we see in our vision is interpreted by our brain, rather than being 100% pure information from the eyes. This is particularly true with large areas of constant colour

The Spots Explained!!!

• The white spots elsewhere in the grid become discoloured by your brain! Our brain has interpreted the black grid.

• As a result, your brain tries to fill in the white circles with the shade of black. In other words, there appears to be slightly smaller black or grey circles dancing around inside the ones you're not looking directly at.

You Cannot See Everything!

• Close your right eye, or cover it with your hand • Stare at the black circle (below) • While looking at the circle, use 'side' (peripheral) vision

to see the cross • Slowly move your head towards the screen • The cross should completely disappear • Move closer, and it will re-appear!

Stare at the dot….

Explanation!!!

• Due to the large amount of white around the circles, once again our vision is interpreted by the brain. The black dot is rigidly defined, whereas everything else fades away to white. After a while, the brain forgets that a series of shaded circles exist, and fills in the information gaps with pure white.

Are the lines squint or straight?

Explanation!!

• The grey lines are indeed straight! Off-setting the black squares gives the impression of perspective, making the lines seem closer together - or further apart. For proof, hold up the edge of a piece of paper to one of the lines, then move down to the one below, and so on.

MAGIC EYE!!!

•Stare at the picture for a few minutes and slowly move your head back… see what appears….

How its done…

• THE FIRST STEP is to create a 3D model.

• THE SECOND STEP is to produce a 2D pattern which will serve as the visible pattern that camouflages the hidden image.

• THE THIRD STEP of the process is the computer program that takes the grayscale source plus the 2D pattern to encode the hidden image.

So….

Remember things aren’t always as they seem…

Color Blindness

• Almost 10% of human males experience color vision deficiency (compared with 0.4% of females). The most common form of these abnormalities is characterized by an inability to distinguish between red and green hues.

• Sometimes the genes we inherit are wrong. When this happens the retina will pick up slightly different colours

• The most common form is red-green colour blindness which means that red and green colours look the same.