PERCEPTUAL VERSUS LATITUDE-BASED 360-DEG VIDEO CODING OPTIMIZATION

In this paper, we present two optimization strategies for the improve- ment of 360-degree video coding efficiency. For the first strategy, the just noticeable difference dedicated to 360-degree images is ob- tained thanks to a novel framework relying on rectilinear projec- tions. The estimated JND is incorporated as a weighting function for the 360Lib-VTM-4.0 RDO scheme in order to make its selection results more correlated with the human perception. The second strat- egy consists of a QP adjustment according to the latitude position in the sphere, where the incorporated weighting factor are modeled using the Von Mises Distribution. In order to evaluate the perfor- mance of both video coding optimization strategies, a set of exper- imental tests are performed using four high resolution 360-degree video sequences. The RDO-based JND strategy outperforms the anchor 360Lib9.0-VTM 4.0 while preserving the perceived image quality. Further, the latitude-based strategy achieves higher perfor- mance when compared to 360Lib9.0-VTM 4.0 and to a state-of-the- art approach [1], in terms of BD-rate of WS-PSNR and CPP-PSNR.