Perception of edge sharpness in three-dimensional images

The quality of 3D images is usually perceived as being better than that of 2D images. In 2D images, edge sharpness is responsible for the quality. Accordingly, we examined the effects of the stereoscopic perception of edge sharpness on image quality by employing the categorized pair comparison method. We compared the sharpness of two types of natural 3D images with 2D images and found that the sharpness of 3D was not always perceived as being sharper than 2D. Next experiments were carried out to examine the role of rivalry on edge sharpness using a geometric image to which a local rivalry was artificially added. Results showed that the artificial local rivalry reduced the edge sharpness. Further experiments compared the sharpness of the vertical or horizontal edges in 3D images, which consisted of two planes (near and far), with that in 2D images. Consequently, the 3D vertical edge was as sharp as the 2D one, while the horizontal edge was perceived as being sharper than the 2D. As a result, the improvement in edge sharpness raises overall 3D image quality. Moreover, the perception of an occluded region in 3D images affected the edge sharpness. We also refer to the relationship between the perception and rivalry that might have caused interocular suppression.