I love optical illusion, and this is perhaps the best color optical illusions I have ever seen. The blue and green spiral stripe are off the same colour. The scientific explanation behind this optical illusion is because our brain judges the color of an object by comparing it to surrounding colors.
Image Source: Akiyoshi Kitaoka (visit this link of the original image)
This is real! Don’t believe me? Test the value of both the color with Photoshop Eyedropper Tool. The RGB value for both are 0, 255, 152. Come to think of it, why is it that color blind people are not able to tell the difference between green and red? Is it because of optical illusion or simply the lack of certain cells in their eye. Wondering.