For a visualisation I use a HDR image for environment texture. It gives image based lighting, it is also reflected in the model and it also appears as a background behind the model.
What I need is that this HDR image continues to affect the model but to use a modified version of this same image to appear as the background behind the model. By a modified version I mean: a far more subdued, faded, colourised, low contrast version of the same image, such as would give a background homogeneous enough to make the model stand out, yet more interesting than a simple gradient.
I know I could render the model without any background and composit the modified image in, but is there a way to do it without compositing? A node setup that separates the image texture that gives IBL/reflections from the background image texture, so I could modify the later without affecting the former?
I am looking for a one-step solution that requires no post production after rendering...