The Reflection Index Render Channel returns an image with floating-point values corresponding to the Fresnel IOR values of scene objects' materials.
This render channel can be used to enhance or reduce Fresnel IOR effects in the final composite. Note that the values generated in this render channel can often be above 1, so that the image may appear to just be black and white. Sampling the pixel values in the white areas returns the precise floating-point values stored, which represent the Fresnel IOR numbers for the rendered object.
V-Ray Material (V-Ray Mtl) is an example of a material with Fresnel IOR parameters that could be represented in this render channel.
