Eye and EEG activity markers for visual comfort level of images

Abstract

Depth perception by binocular cues is based on the matching of image features from one retina with corresponding elements from the second retina. However, high disparities are related to the higher visual discomfort levels and may cause the eye fatigue during extended stereoscopic perception time. The goal of the investigation was to find a set of measurable features for stereoscopic image visual comfort level prediction. The investigation involved gaze, pupillometric and EEG data from 28 subjects who evaluated visual comfort level of 120 stereoscopic images. Six different time frame windows were used to analyze four measured features: the number of focus points; the dynamics of pupil size; disparity level at the focus points; the activity of EEG bands at the frontal lobe. A significant difference was found in all investigated stereoscopic image groups. 2-s and 5-s pre-DPI window showed best results for the selected feature sets. The higher disparity at the focus points, lower number of focus points are related to the lower levels of visual comfort. However, features such as the number of focus points, the pupil size and the disparity level for the images with lowest visual comfort scores showed similar results to the images scored as “comfortable” or “very comfortable”.