Ok, now we have the colour/diffuse map for the model. What we have to do now is to create a mask based on the intensity of this map. It's a great way to get information about the bump/displace of the real photo.

Now we can use some tricks in Zbrush. Using the commands inflate and smooth, on the deformation menu, we can apply a "bump" on the model and with this technique you get a great base to start to deform your model with the traditional tools of Zbrush, inflate brush, projection master etc.

This is the model after some adjusts.

Now we can export the bump/displace to use in 3dsmax.