Cool, says the book geek

By Japanese art director and copywriter Masashi Kawamura, the Rainbow In Your Hand flip book has an image of the color spectrum against a black background on each page. As you flip through the pages, it creates an illusion of a rainbow that seems to be suspended in the air above the book.

Here's another view:


Thanks to Bibliofuture of LISNews for the link to the first video and the information behind it.