Stereo image quality: Effects of mixed spatio-temporal resolution

We explored the response of the human visual system to mixed-resolution stereo video-sequences, in which one eye view was spatially or temporally low-pass filtered, It was expected that perceived quality, depth, and sharpness would be relatively unaffected by low-pass filtering, compared to the case where both eyes viewed a filtered image. Subjects viewed two 10-second stereo video-sequences. in which the right-eve frames were filtered vertically (V) and horizontally (H) at 1/2 H, 1/2 V, 1/4 If, 1/4 V, 1/2 H 1/2 V,1/2 H 1/4 V, 1/4 B 1/2 V,and 1/4 H 1/4 V resolution, Temporal filtering was implemented for a subset of these conditions at 1/2 temporal resolution, or with drop-and-repeat frames, Subjects rated the overall quality, sharpness, and overall sensation of depth. It was found that spatial filtering produced acceptable results: the overall sensation of depth was unaffected by low-pass filtering, while ratings of quality and of sharpness were strongly weighted towards the eye with the greater spatial resolution, By comparison, temporal filtering produced unacceptable results: held averaging and drop-and-repeat frame conditions yielded images with poor quality and sharpness, even though perceived depth was relatively unaffected. We conclude that spatial filtering of one channel of a stereo video-sequence may be an effective means of reducing transmission band width.