Photoshop isn't magic but it has come a long way since since version 6.01. Most people know about the standard X-ray Photoshop techniques using the curves, levels and burn features, but are not aware of the many other features that are available in the latest version of Photoshop. Using these advanced features you can enhance an image at the level of the pixel and 60% of the time reveal more than the naked eye can see. Here's how.
Open the image and use the pen tool to select only the area you want to reveal.
Go to the Channel Mixer (Image>Adjustments) & select Infrared. Set the constant to -55.5%.
Go to Exposure (Image>Adjustments) and take it up to +5.88). It should roughly look like the image to the left now.
Go to the High Pass (Filter>Other) and bump it up to about 80. This is where the flesh will shine through.
Now apply a Gaussian Blur to the area to even it out. Up the contrast too until it looks smooth.
Finally, use the Levels tool to get the nipples (or other details) to stand out more.This technique should work on most Photoshops after 6.01 and it should work 60% of the time