I’m a photographer in New York working on a “Digital X-Ray” tattoo photo project. I’m turning my photographs into a book. I shoot the tattoo with my Nikon D5000, transfer the image to my iPad, scale and align the tattoo to the right spot and then shoot the “Digital X-Ray.” 

Alignment and scale are very important. That is probably the most time-consuming and difficult part. For the models, I give them great credit holding the iPad over their shoulders steadily with a very light grip on the edges. 
Many of the models have fascinating stories associated with certain tattoos which I am including in the finished book. So many of the tattoos go unseen because of they are covered by clothes or hair. Sometimes the model themselves barely ever see the tattoos like the ones on the backs of their necks. This is a way to show off the art.

More info: johnrennhack.com

Jess

Cat

Egan

Nicki

Julie

Melissa

Abigail

Nicki

Sarah