Texture orientation modulation for halftoning watermarking
In this paper, a halftoning-based watermarking scheme with high data capacity and image quality is presented. Three types of watermarks of various pixel-depths, including 1-bit, 2-bit, and 3-bit, are able to be embedded without prominently damaging the image quality. To achieve high marked image quality, the parallel-oriented high efficient Direct Binary Search (DBS) halftoning is adopted to cooperate with the proposed Orientation Modulation (OM) method. In the decoder, the Least-Mean-Square-trained (LMS-trained) filters are adopted to extract the features of marked images in the frequency domain, and the naïve Bayes classifier is employed to analyze the extracted features and further decode the watermark information. Experimental results demonstrate that the proposed DBS-based OM encoding scheme provides excellent image quality, high processing efficiency, and high robustness to adapt to practical printing application.