Watermarking text documents has become a cutting-edge research topic due to the increasing demand of protecting text documents from illegal copying, tampering, distribution and selling. When presenting a document on the computer screen, many existing text watermarking methods struggle in embedding large amounts of watermarks into documents invisibly to resist the most common screenshot attack. To deal with this problem, we present a screenshot resistant watermarking method for text documents based on font adaptive modification. In the proposed method, we generate a font variant to represent the watermark with high invisibility by adaptivly shifting the centroid of glyphs. The font variant is deemed watermarked and will be used for creating watermarked text documents. For watermark extraction, we exert a novel projection method with the support of semantic information to precisely segment glyphs in the document screenshot. The watermark is then recovered by analyzing the corresponding centroid shift of glyphs. Unlike the previous font-based watermarking method that alters the font of every glyph, we leave half of the glyphs with original font unchanged and use them to represent bit '0', which greatly improves the invisibility. Moreover, we achieve a high payload with one bit per glyph which outperforms the previous text document watermarking method. Experimental results evaluated on English and Chinese documents show that the proposed method is more robust and introduces less visual distortion than the previous method, which verify the superiority and applicability of our work.

Video Internet of Things (IoT) is widely used in the fields of safe city, smart transportation, and logistics warehousing, which facilitates the acquisition of important environmental and semantic information. However, the tampering of unauthorized video data may seriously violate user privacy and even harm society. Although the existing video watermarking technology provides an effective solution for copyright protection, it still faces challenges to achieve robust copyright authentication in the complex IoT environment. In this article, a robust blind video watermarking based on ring Tensor and Bose-Chaudhuri–Hocquenghem (BCH) coding is proposed. First, ring sub-bands of different sizes are constructed in the spatial domain of the video, and the ring sub-bands of consecutive video frames are combined into a ring tensor for copyright watermark embedding. Second, to balance the imperceptibility and robustness of the copyright watermark, an adaptive BCH coding scheme is developed, which uses the modified differential entropy to calculate the video complexity and automatically selects the appropriate watermark coding parameters. Finally, a quaternary synchronization watermark embedding strategy is designed to solve the time synchronization destruction caused by video frame rate conversion. A synchronization ring is constructed within each video frame using the strong correlation between adjacent frames. When the video is subjected to temporal synchronization attacks, the synchronization watermark is extracted from the synchronization ring to restore the synchronization of the copyright watermark. Extensive experimental results demonstrate that the proposed scheme can effectively resist common video processing while exhibiting excellent robustness against video attacks in complex Internet environments.

An efficient and reliable digital watermarking scheme is needed in a complex network environment to solve image copyright disputes. However, most existing digital watermarking technologies can only resist common image processing and perform poorly against complex attacks. To this end, an adaptive robust watermarking for resisting multiple distortions in real scenes is proposed in this work. First, to reduce the impact of common attacks on the robustness of the algorithm, two-level stationary wavelet transform (SWT) is applied to extract low-frequency sub-band of host image, which is subsequently divided into nonoverlapping sub-blocks. Then, a circular sub-block method is designed for watermark embedding. Moreover, an improved Schur decomposition is proposed to control the variation range of eigenvalues. Meanwhile, an adaptive robust factor and embedding strength strategy are proposed to ensure image reconstruction in real number field, thereby balancing the invisibility and robustness of the watermark. Finally, the logistic encryption and repetition code are performed on the watermark to improve the security and error correction capabilities of the watermark. Extensive experiments demonstrate that the proposed scheme has higher performance than some representative watermarking schemes in complex combined attacks and real-world scenarios.

As a secondary generation method, video recording will cause irreversible damage to the watermark within the video, which has always been challenging in video forensics. Although many video watermarking methods are reported in the literature, these methods, however, still cannot well resist camera recording. This has motivated the authors in this paper to introduce a new video watermarking method to resist camera recording. For the proposed method, two watermarks, i.e., copyright watermark and synchronization watermark, are embedded into the well-selected frequency domain coefficients. The synchronization watermark is used to ensure that the copyright watermark can be successfully extracted at the decoder side. To extract the copyright watermark without manual assistance, a neural network based segmentation model is applied to identify the watermarked video-playing region in the camera-recorded video. Meanwhile, automatic perspective correction is performed on the watermarked video-playing region so that the watermark information can be extracted accurately. The experiments show that the watermark data can be embedded into the raw video successfully and extracted from the camera-recorded video accurately by applying the proposed method. And, the proposed method significantly outperforms related works in terms of robustness in different scenarios, which has verified the superiority and applicability of the proposed method.

Video watermarking based on frequency domain is proved to have good invisibility and robustness. However, most of the existing video watermarking schemes embed watermarks in the frequency domain based on subblock segmentation, while ignoring the variation relationship between video space and frequency domain features. Therefore, it is difficult to achieve robust authentication in complex application scenarios. In this paper, a ring subband is constructed in DT-CWT domain as the watermark embedding region by analyzing the relationship between video space and frequency domain characteristics under multiple attacks. Subsequently, the double watermark is embedded by modifying the DCT coefficient of the ring subband, with the copyright watermark alternately and repeatedly embedded within the ring subband, and the synchronous watermark is embedded in the outermost concentric circle. In addition, visual encryption (VC) and piecewise linear chaotic mapping (PLCM) methods are used to encrypt the watermark before it is embedded in the concentric rings, and two shared images are generated, one for the watermark embedding stage and the other for the watermark extraction stage. Experimental results demonstrate that the proposed scheme can resist common attacks, such as noise, JPEG compression, rotation, scaling, time synchronization attacks, and its robustness surpasses existing discrete wavelet transform (DWT) and DT-CWT based video watermarking schemes under complex attack scenarios.