1. A three dimensional display system comprising: a display presenting a plurality of views of a scene, each view corresponding to a viewing direction for the scene; a rendering unit generating a respective image for each of the plurality of views, the rendering unit being capable of generating differentiated images for neighboring views containing differentiated image data providing a three dimensional depth effect when neighboring views are viewed by different eyes of a viewer; a user processor generating a user presence estimate in response to an attempted detection of a user in a viewing area for the display system, the presence estimate including an orientation of the user; and a data processor: receiving the user presence estimate; and modifying the differentiated images for the neighboring views to adapt the three dimensional effect in response to the determined orientation of the user, wherein the differentiated images are gradually transitioned over a known time from a first mode of three dimensional effect to a second mode of three dimensional effect in response to a detection of a change in the user presence estimate, the first mode of three dimensional effect corresponding to a reduced three dimensional effect relative to the second mode of three dimensional effect.