There's No Blue In This Image

Or is there? It depends on whether you think color is something that happens inside your brain or a quality of a surface. In any case, this image contains no blue pixels. None at all. The boxes appear blue by virtue of the contrast with the brown/orange color in the image. Check it in Photoshop, if you don't believe it.
It is another interesting example of color constancy. The image was produced by Japanese professor Akiyoshi Kitaoka.