Enhancement of Viewer Comfort in Stereoscopic Viewing: Parallax Adjustment

reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the SPIE. ABSTRACT One of the major deeciencies of stereoscopic visualization, viewer discomfort, can be caused by the non-robustness of human perception (hyper-sensitivity to 3-D) or by excessive 3-D cues in the viewed images. In order to minimize this discomfort, the amount of parallax (or "3D-ness") within each stereo pair needs to be reduced. Similarly to the case of "continuous look-around", parallax adjustment requires the knowledge of images from virtual cameras. In the case of parallel geometry, the virtual cameras are located on the line between the true cameras. Since in a general scenario no constraint should be posed on the complexity of the viewed scene, 3-D modeling techniques cannot be used. We evaluate the usefulness of parallax adjustment using two view reconstruction methods based on disparity-compensated linear interpolation: a quadtree method with block splitting adapted to object boundaries and a pixel based (dense) method. For all, but most complex, stereoscopic images tested (ITU-R 601 from CCETT and NHK) both algorithms performed very well, especially the pixel-based approach. In terms of the overall usefulness of parallax adjustment, the initial tests have shown a very favorable viewer response; the perceived depth was judged to vary smoothly from zero (one virtual camera) through natural 3-D (true cameras) to exaggerated 3-D (virtual cameras further apart than the true cameras-extrapolation). The adjustment was convincing although not completely free of distortions.