Impact of downsampling ratio in mixed-resolution stereoscopic video

In mixed-resolution (MR) stereoscopic video, one of the views has a lower resolution compared to the other one, hence providing means for improved compression. The underlying assumption in MR stereoscopic video is that the human visual system fuses the left and right views in such a way that the perceived image quality is close to that of the higher-resolution view. This paper describes a subjective quality evaluation experiment with uncompressed MR stereoscopic video, in which the aim was to discover the approximate limit of the downsampling ratio where the perceived quality is still close to the quality of the higher view. Different downsampling ratios, namely 1/2, 3/8, and 1/4 along both coordinate axes, were tested. The threshold of the higher-resolution view being dominant in the perceived quality lied in between downsampling ratios 1/2 and 3/8, corresponding to 11.4 and 7.6 pixels per degree of viewing angle, respectively. At downsampling ratios 3/8 and 1/4, the perceived quality linearly correlated with the average luma peak signal-to-noise ratio of the lower-resolution view.