Extruding pattern base on grey scale of Image sample

Hi Everyone, 

I'm very new to grasshopper, so any help will be tremendously appreciated. 

Attached are my Rhino3D file as well as my GH file. This is for a school assignment.

I had created a pattern using hoopsnake and from there had successfully mapped it onto my surface and even extruded it, which is good... but... the next phase, I need to extrude the pattern from the rhino surface based on the grey scale of a chosen image. Meaning I'll need to put a image sampler and use that to create parameters for the extrusion. The extruded heights need to relate to the grey scale of the image. 

I have no idea how to do this... Please help!!