Is this for real or is this photoshop?

There is a detailed explanation of the tattoo, which describes the physics behind the Fourier Transforms rather well.

Anyway, the tattoo shows the Fourier transform, one of the most extraordinary accomplishments in mathematics. It is due to Jean Baptiste Joseph Fourier, 1768-1830. I won’t put his picture here because he’s butt ugly. Anyway JB realized that in a way, a different universe lives beside us. We are accustomed to x, y, z and t. x is horizontal, y is vertical, z is near-far, and t is time. Everything we can feel and intuit is expressed in these terms. But entangled in this Cartesian universe is another one, a jiggly world of images and sounds and signals and waves.

Anyway, sound is a frequency-domain phenomenon. You can’t understand it in the space-time domain. Some things are strictly space-time, and other things can be seen either way. You might be amazed at how useful it is to look at the visual world in the frequency domain. In fact, that’s how our brain does it. Everything passes through a kind of Fourier transform before the higher visual processing centers do anything with it. Visual computation, for the most part, follows frequency analysis. You have to admit–The Foomeister was definitely the man.

Source David Bradley’s blog  (seems to be down for now)

There is a joke floating around that you know you are a real physicist, when you go to the beach and see the waves, and the first thing that comes to your mind is the Fourier Transforms!