Calculating linear RGB specular values of metallic surfaces with a given IOR

Hey there.

I was wondering if anyone out there knew how to get the linear spec values for each respective RGB channel on metallic surfaces from a give index of refraction. I have been using a furmula which works well with dielectric materials, but that math doesn’t work for metallic surfaces (the values are way to low, and furthermore it’s greyscale).

For dielectric materials in my python script i use this formula where IOR is the index of refraction:

IOR = raw_input (’ ')
Linear =(float(IOR)-1)**2/(float(IOR)+1)**2

Thanks!