Variation control on noise

Unfortunately there is no way to feed image data into grey inputs.

Instead of changing the noise variation, you can achieve the same result by using the color data to offset the noise (with the offset component). Use HDR values to make sure there is no repetition. For example, offset X by 1.0 for each tile. Or if you're using perlin noise and want to keep it clean, generate the noise within the map script using get_perlin_noise(x,y,z,scale).

I really wish there was a component that takes 1 sample from an image input and converts it into a gray control value. Or this could be done automatically when connecting green to grey. I guess there's some fundamental issue with FF architecture that prevents this - or else it would already be there.