Image Sampler Issues

I am trying to use an infrared image to create a landscape based on the color of the image.  I haven't been able to figure out how to set height scales for the different colors.

I wanted to map this height information on a mesh grid that I could animate.

I will have several images that will hopefully produce different colors and heights of the exact same image.

Has anyone been able to get image sampler to recognize/analyze color?