Removing the cardboard effect in stereoscopic images using smoothed depth maps

Depth maps are important for generating images with new camera viewpoints from a single source image for stereoscopic applications. In this study we examined the usefulness of smoothing depth maps for reducing the cardboard effect that is sometimes observed in stereoscopic images with objects appearing flat like cardboard pieces. Six stereoscopic image pairs, manifesting different degrees of the cardboard effect, were tested. Depth maps for each scene were synthesized from the original left-eye images and then smoothed (low-pass filtered). The smoothed depth maps and the original left-eye images were then used to render new views to create new "processed" stereoscopic image pairs. Subjects were asked to assess the cardboard effect of the original stereoscopic images and the processed stereoscopic images on a continuous quality scale, using the doublestimulus method. In separate sessions, depth quality and visual comfort were also assessed. The results from 16 viewers indicated that the processed stereoscopic image pairs tended to exhibit a reduced cardboard effect, compared to the original stereoscopic image pairs. Although visual comfort was not compromised with the smoothing of the depth maps, depth quality was significantly reduced when compared to the original.