Boosting paired comparison methodology in measuring visual discomfort of 3DTV: performances of three different designs

The pair comparison method is often recommended in subjective experiments because of the reliability of the obtained results. However, a drawback of this method is that the number of comparisons increases exponentially with the number of stimuli, which limits its usability for a large number of stimuli. Several design methods that aim to reduce the number of comparisons were proposed in the literature. However, their performances in the context of 3DTV should be evaluated carefully due to the fact that the results obtained from a paired comparison experiment in 3DTV may be influenced by two important factors. One is the observation error from observer's attentiveness, in particular inverting the vote. The second factor concerns the dependence on the context in which the evaluation takes place. In this study, three design methods, namely Full Paired Comparison method (FPC), Square Design method (SD) and the Adaptive Square Design method (ASD) were evaluated by subjective visual discomfort experiment in 3DTV. The results from the FPC method were considered as the ground truth. Comparing with the ground truth, the ASD method provided the most accurate results with a given number of trials. It also showed the highest robustness against observation errors and interdependence of comparisons. Due to the efficiency of the ASD method, paired comparison experiments become feasible with a reasonably large number of stimuli for measuring 3DTV visual discomfort.