Displacement Maps - making Waves and brains

1. duplicate the image ( it must be the same size)

2. change the copy to grayscale ( image ->mode)

3. save the copy as "map.psd"

4. open the second image ( filing cabinet in this case)

5. shift drag it onto the original image

6. change it to a smart object ( layer -> smart object)

7. choose filter-> displace and select "map.psd"

8. use a blend mode of multiply

9. change the opacity to suit

10. create a layer mask and erase any parts you don't want

for the images below, I filled the copy with white and painted in a pattern of black stripes. When it was blended, the opacity was reduced to create the desired effect