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.
The Red of Painters
For a long time, it was the chapter on reds that began the exposition on pigments useful to painters. That was already the case in Pliny’s Natural History, which had more to say on red than on any other color. And the same is true for the collections of the medieval recipes intended for illuminators and in the treatises on painting printed in Venice in the sixteenth and seventeenth centuries.
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Not a Trivial App
The British newspaper The Telegraph recently published an interesting interview with Ton Büchner, ceo of Dutch coatings giant AkzoNobel. He spoke out about AkzoNobel's Colour Visualizer app.
Five years into the role – his predecessor did nine – he’s already starting to think that if his first act was about financial performance, what his second act will be. Accelerate organic growth, add acquisitions, and accelerate innovations, he says, pointing out he’s already started to do all three.Innovations are clearly high on his agenda. He points to a colleague’s iPhone that is showing a smartphone application which allows a customer to take a picture of a wall in their home and then see how it would look covered in different Dulux paints. If they like how it looks, they can order tester strips to be posted to allow them to try it out.
“People start sitting at home on their sofa saying, 'I think I want a change.’ Then they go to a B&Q or Homebase or one of our own stores, as we have a lot of those in the UK, and they stand in front of a rack of paint. Between the wish and what do I buy now, there is this gap which makes people a bit dazed.
“Initially, people said, 'Ah, this visualiser, this is just a gimmick. But we’ve had 13 million downloads globally. It’s not a trivial app."
Please Check Out our Competitors
As you may know, we operate a color rendering service Professional clients such as paint contractors, paint brands and designers send us pictures of buildings. We make the pictures interactive so that they can be colored. This helps our clients to sell their colors and designs to their customers. The photo below can be colored here. 
From time to time we put our competitors', as well as our own color rendering service, to the test. Recently we submitted a real-life job, which was first submitted to us by one of our own clients, to some of our competitors. We think it's healthy to keep an eye on our own performance, in comparison to others. For your information, we share the results with you. The images below have been rendered with similar colors. But as you can see, not all colors are created equal. The full report can be downloaded here. 
Mobile Color Measurement for Real?
The last couple of years we've been bombarded with apps that claim to measure color. The procedure is simple: take a picture of a colored object and the app will tell you which paint color comes closest. However, these apps never deliver as promised. Most measurements are off, not even close. Your green could easily become blue, your brown becomes red. The reason is simple: colors in a photo are subject to lighting, which hugely affects the color of the surface. This is explained in the very first post on our weblog: 'What is Color?'
As a result, colors can only be measured reliably with an additional hardware measurement device that has its own standarized light source. There are some on the market which are small and can be coupled with your smartphone. Which is great, but still requires you to purchase and carry around an extra device. However, some German scientists may have come up with a solution, the HawkSpex app. Their app uses the smartphone screen as a light source. 
By manipulating the light of the screen, they managed to turn a smartphone into a full-fledged spectrophotometer. Spectros are great. Not only do they allow you to measure colors reliably, they can also tell a lot about the chemical components of an object. The latter feature is used by the new app to test if food is safe to eat. But considering that the smartphone is turned into a spectro, it seems only a matter of time before someone comes up with an app to reliably match a surface to paint color.
Tarantula Blue
Structural colors are on the rise. Structural coloration is the production of color by nano structured surfaces, rather than pigments. Peacock feathers and butterfly wings are examples of structural color.
Lately we've seen many research papers appearing on the subject. A recent one is here, by the Karlsruhe Institute of Technology in Germany. Their work is a follow up on the work we reported on earlier here. After imitating Tarantula blue, they now discovered a way to make the color consistent when viewed from different angles. 
Structural colors aren't ready for prime-time yet. But that only seems a matter of time...