A stereoscopic display comprising: a sensor configured to detect a first angle of a first head roll of a first viewer and to detect a second angle of a second head roll of a second viewer; and an image renderer coupled to the sensor, wherein the image renderer is configured to: adjust a direction of disparities between a first image and a second image of a 3D image according to the first angle of the head roll of the viewer, wherein one of the first image and the second image is a left image and the other one of the first image and the second image is a right image; adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image to form a first relocated second image; adjust the direction of the disparities between the first image and the second image according to the second head roll; and adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image according to the second head roll to form a second relocated second image, wherein the first image is configured to be commonly seen by the first viewer and by the second viewer, wherein the first relocated second image is configured to be seen by the first viewer, and wherein the second relocated second image is configured to be seen by the second viewer. a sensor configured to detect a first angle of a first head roll of a first viewer and to detect a second angle of a second head roll of a second viewer; and an image renderer coupled to the sensor, wherein the image renderer is configured to: adjust a direction of disparities between a first image and a second image of a 3D image according to the first angle of the head roll of the viewer, wherein one of the first image and the second image is a left image and the other one of the first image and the second image is a right image; adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image to form a first relocated second image; adjust the direction of the disparities between the first image and the second image according to the second head roll; and adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image according to the second head roll to form a second relocated second image, adjust a direction of disparities between a first image and a second image of a 3D image according to the first angle of the head roll of the viewer, wherein one of the first image and the second image is a left image and the other one of the first image and the second image is a right image; adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image to form a first relocated second image; adjust the direction of the disparities between the first image and the second image according to the second head roll; and adjust the direction of the disparities by keeping the first image static and by relocating the second image with respect to the first image according to the second head roll to form a second relocated second image, wherein the first image is configured to be commonly seen by the first viewer and by the second viewer, wherein the first relocated second image is configured to be seen by the first viewer, and wherein the second relocated second image is configured to be seen by the second viewer.