 Phantograms are usually placed horizontally and are intended to be viewed standing back from the image, though they can also be placed vertically and viewed at an angle from above or below.Phantograms work by presenting the viewer with a pair of flat images precisely distorted to mimic the anticipated perspective of a three-dimensional object viewed from the phantogram's intended vantage point.As with other forms of stereoscopy, the illusion reproduces many of the visual cues associated with binocular depth perception, fooling the viewer's vision into perceiving the two-dimensional images as having actual depth.