Using VRayNormals to enhance your renders

The Normals Render Element creates a normals image from surface normals in the scene. It stores the camera space normal map using the geometry's surface normals. The Normals Render Element is useful for adjusting lighting in the composite. For example, the red, green and blue channels can be adjusted in compositing software. 

The Normals Render Element is useful for changing the appearance of lighting in a scene in a composite without the need for re-rendering.