Not all optical illusions use colours, for example some use black and white (which are technically shades, to be pedantic). And also the reason that optical illusions mainly use colour is because the...
There are many kinds of optical illusions, and many of them do not depend upon colour, only shape. So, colour blindness affects some optical illusions but not all of them.
An optical illusion is something that appears real but actually isn't. All kinds of optical illusions can be generated with mirrors, overlapped negatives, photography, etc.
I believe we have optical illusions to make our eyes and brains think in different ways then they normally think! Without optical illusions, we wouldn't look at things the way we look at them... i...
An optical illusion is something that tricks your brain into thinking an image is positioned or placed one way, but really is placed another way or has a multitude of positions