Photoshop X-ray Guide How Do U Get An X-ray Effect On Photoshop?

How do u get an x-ray effect on Photoshop? - photoshop x-ray guide

I have some pictures of the different parts of a skeleton of my project and just want to know how the picture seems to have been obtained for the X-rays, with Photoshop. If you know could be a step by step guide for me, please!