Thermal Vision Operative

I took one of my drawings ([link]), and put it on a photo background. I changed the colours using gradient mapping. To get the thermal vision effect on his body I first highlighted the body parts which aren't visible under the coat using the dodge tool. This made it so that the gradient map would apply the yellows to the places where the body parts are underneath the coat. I also selected some random objects in the background and gave them slight colour changes, like a few pipes and an air conditioner or something.