Ownership protection for light-field 3D images: HDCT watermarking

Watermarking plays an important role in ownership protection. The embedding strength of the watermark determines the robustness of the watermark and affects the imperceptibility of the watermark. Setting appropriate embedding parameters can balance the robustness and imperceptibility of the watermark. Considering the high-dimensional characteristics of the light-field 3D image, we decide to extract more features from the light-field image to control the embedding parameters accurately to improve the visual quality of the watermark. Therefore, in this paper, we present a method of ownership protection for the light-field image based on high-dimensional color transform (HDCT) watermarking. Our paper introduces an HDCT space to unify multiple different color spaces, rather than selecting a specific color space for processing. By mapping low-dimensional RGB colors into high-dimensional color space, in which the feature vectors can separate the salient region from the background linearly, and extract the embedding parameters accurately. The experimental results show the superiority of the proposed algorithm compared with the existing light-field watermarking algorithm, from the two aspects of imperceptibility and robustness. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement