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
It might or might not, depending on the illusion and the type of color blindness. Alternatively, it's possible they might see something, but different from what a trichromat (normally sighted person)...