Investigating how people perceive virtual reality (VR) videos in the wild (i.e., those captured by everyday users) is a crucial and challenging task in VR-related applications due to complexauthenticdistortionslocalizedinspaceandtime.Existingpanoramic video databases only consider synthetic distortions, assume fixed viewing conditions, and are limited in size. To overcome these shortcomings, we construct the VR Video Quality in the Wild (VRVQW) database, containing 502 user-generated videos with diverse content and distortion characteristics. Based on VRVQW, we conduct a formal psychophysical experiment to record the scanpaths and perceived quality scores from 139 participants under two different viewing conditions. We provide a thorough statistical analysis of the recordeddata, observing significantimpact of viewing conditions on both human scanpaths and perceived quality. Moreover, we develop an objective quality assessment model for VR videos based on pseudocylindrical representation and convolution. Results on the proposed VRVQW show that our method is superior to existing video quality assessment models.We have made the database and code available at https://github.com/ limuhit/VR-Video-Quality-in-the-Wild.

Omnidirectional images (also referred to as static 360$^{\circ }$panoramas) impose viewing conditions much different from those of regular 2D images. How do humans perceive image distortions in immersive virtual reality (VR) environments is an important problem which receives less attention. We argue that, apart from the distorted panorama itself, two types of VR viewing conditions are crucial in determining the viewing behaviors of users and the perceived quality of the panorama: the starting point and the exploration time. We first carry out a psychophysical experiment to investigate the interplay among the VR viewing conditions, the user viewing behaviors, and the perceived quality of 360$^{\circ }$images. Then, we provide a thorough analysis of the collected human data, leading to several interesting findings. Moreover, we propose a computational framework for objective quality assessment of 360$^{\circ }$images, embodying viewing conditions and behaviors in a delightful way. Specifically, we first transform an omnidirectional image to several video representations using different user viewing behaviors under different viewing conditions. We then leverage advanced 2D full-reference video quality models to compute the perceived quality. We construct a set of specific quality measures within the proposed framework, and demonstrate their promises on three VR quality databases.

In this paper, we propose an effective blind image quality assessment (BIQA) method for stereoscopic images by deep neural network (DNN) of multi-level feature fusion (MLFF) inspired by the multi-scale characteristics and binocular properties of the human visual system (HVS). Specifically, we firstly feed the left- and right-view images into a weight sharing convolutional neural network (CNN) for jointly feature extraction. To aggregate multi-level features, we concatenate the low-, middle-, and high-level feature maps of stereoscopic images to simulate the complicated visual interaction processing in the HVS. Two fully connected layers are used to build the nonlinear mapping from the highly abstract features to the quality scores of stereoscopic images. The experiments conducted on two public databases prove the validity of the proposed MLFF method.