  Omnidirectional images and videos can provide immersive experience of
real-world scenes in Virtual Reality (VR) environment. We present a perceptual
omnidirectional image quality assessment (IQA) study in this paper since it is
extremely important to provide a good quality of experience under the VR
environment. We first establish an omnidirectional IQA (OIQA) database, which
includes 16 source images and 320 distorted images degraded by 4 commonly
encountered distortion types, namely JPEG compression, JPEG2000 compression,
Gaussian blur and Gaussian noise. Then a subjective quality evaluation study is
conducted on the OIQA database in the VR environment. Considering that humans
can only see a part of the scene at one movement in the VR environment, visual
attention becomes extremely important. Thus we also track head and eye movement
data during the quality rating experiments. The original and distorted
omnidirectional images, subjective quality ratings, and the head and eye
movement data together constitute the OIQA database. State-of-the-art
full-reference (FR) IQA measures are tested on the OIQA database, and some new
observations different from traditional IQA are made.
