Spherical Light-Weight Data Hiding in 360-Degree Videos With Equirectangular Projection

In this paper, we propose a spherical light-weight data hiding technique for 360-degree videos with equirectangular projection between sphere and plane. In particular, computationally efficient least significant bit (LSB) data hiding is applied to the color encoded equirectangular projection of the sphere. As viewers put more attention to the areas around the equator of a 360-degree video compared to the poles, LSB data hiding may be performed in the regions around the poles without causing perceptually significant quality degradation. In addition, the equirectangular projection induces a huge amount of data redundancy in the areas near the poles which increases the capacity available for LSB data hiding. A performance assessment of the proposed spherical light-weight data hiding technique is conducted using the weighted-to-spherically-uniform peak-signal-to-noise ratio (WS-PSNR) and the Craster parabolic projection PSNR (CPP-PSNR). Because both metrics take the non-linear relationship between samples on the sphere and the samples mapped to the plane into account, they are well suited for assessing the performance of the spherical LSB data hiding technique. Numerical results are provided for scenarios in which a 360-degree cover video carries a secret video using different numbers of bit planes. It is shown that video fidelity in terms of WS-PSNR and CPP-PSNR is indeed kept high in the 360-degree stego-video as long as the LSB data hiding is performed in the areas around the poles.