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With the rise of short video and the development of self-media, video has become a type of frequently used data, thus the protection of video data is particularly important. Digital watermarking is a very effective digital authentication and copyright protection technology that hides a piece of data called watermark into digital multimedia content. However, most existing video watermark algorithms fail to deal with the videos under geometric distortions, and they only focus on copyright protection, ignoring the task of tamper detection. This paper proposes a multipurpose video watermarking algorithm that is resistant to rotation and scaling attacks while providing both copyright protection and tamper detection. We design a DFT template embedding method to make the watermarking algorithm resistant to rotation and scaling attacks efficiently. This method can detect the rotation and scaling that the video has undergone during the watermark extraction process, and then extract the copyright watermark information based on geometric correction. In addition, we propose a robust watermark embedding method with tamper detection function, which embeds copyright watermark information with validation bits in the DCT coefficients of I frames. By embedding the copyright watermark block by block, the algorithm can not only improve the robustness, but also enable the system to detect tampering. Experiments show that the proposed algorithm has good robustness to various attacks such as compression, filtering, rotation, scaling, frame rate changing and other inter-frame operations, and it outperforms previous geometrically robust algorithm by an average of 12.8% under geometric attacks on the normalized correlation values. Also, we show that our algorithm is effective in tamper detection by localizing the distorted areas in the video frames. [ABSTRACT FROM AUTHOR]

For covert communication in lossy channels, it is necessary to consider that the carrier of the hidden watermark will undergo multiple image-processing attacks. In order to ensure that secret information can be extracted without distortion from the watermarked images that have undergone attacks, in this paper, we design a novel fragmented secure communication system. The sender will fragment the secret data to be transmitted and redundantly hide it in a large number of multimodal carriers of messenger accounts on multiple social platforms. The receiver receives enough covert carriers, extracts each fragment, and concatenates the transmitted secret data. This article uses the image carrier as an example to fragment the text file intended for transmission and embeds it into a large number of images, with each fragment being redundant and embedded into multiple images. In this way, at the receiving end, only enough stego images need to be received to extract the information in each image, and then concatenate the final secret file. In order to resist various possible attacks during image transmission, we propose a strong robust image watermarking method. This method adopts a watermark layer based on DFT, which has high embedding and detection efficiency and good invisibility. Secondly, a watermark layer based on DCT is adopted, which can resist translation attacks, JPEG attacks, and other common attacks. Experiments have shown that our watermarking method is very fast; both the embedding time and the extraction time are less than 0.15 s for images not larger than 2000 × 2000 . Our watermarking method has very good invisibility with 41 dB PSNR on average. And our watermarking method is more robust than existing schemes and robust to nearly all kinds of attacks. Based on this strong robust image watermarking method, the scheme of fragmenting and hiding redundant transmission content into a large number of images is effective and practical. Our scheme can 100% restore the secret file completely under different RST or hybrid attacks, such as rotation by 1 degree and 5 degrees, scaling by 1.25 and 0.8, and cropping by 10% and 25%. Our scheme can successfully restore the secret file completely even if 30% of received images are lost. When 80% of received images are lost, our scheme can still restore 61.1% of the secret file. If all stego images can be obtained, the original text file can be completely restored. [ABSTRACT FROM AUTHOR]

Watermarking is an excellent solution to protect multimedia privacy but will be damaged by attacks such as noise adding, image filtering, compression, and especially scaling and cutting. In this paper, we propose a watermarking scheme to embed the watermark in the DWT-DCT composite transform coefficients, which is robust against normal image processing operations and geometric attacks. To make our scheme robust to scaling operations, a resampling detection network is trained to detect the scaling factor and then rescale the scaling-attacked image before watermark detection. To make our scheme robust to cutting operations, a template watermark is embedded in the Y channel to locate the cutting position. Experiments for various low- and high-resolution images reveal that our scheme has excellent performance in terms of imperceptibility and robustness. [ABSTRACT FROM AUTHOR]

Portable document format (PDF) files are widely used in file transmission, exchange, and circulation because of their platform independence, small size, good browsing quality, and the ability to place hyperlinks. However, their security issues are also more thorny. It is common to distribute printed PDF files to different groups and individuals after printing. However, most PDF watermarking algorithms currently cannot resist print–scan attacks, making it difficult to apply them in leak tracing of both paper and scanned versions of PDF documents. To tackle this issue, we propose an invisible digital watermarking technology based on modifying the edge pixels of text strokes to hide information in PDFs, which achieves high robustness to print–scan attacks. Moreover, it cannot be detected by human perception systems. This method focuses on the representation of text by embedding watermarks by changing the features of the text to ensure that changes in these features can be reflected in the scanned PDF after printing. We first segment each text line into two sub-blocks, then select the row of pixels with the most black pixels, and flip the edge pixels closest to this row. This method requires the participation of original PDF documents in detection. The experimental results show that all peak signal-to-noise ratio (PSNR) values of our proposed method exceed 32 dB, which indicates satisfactory invisibility. Meanwhile, this method can extract the hidden information with 100% accuracy under the JPEG compression attack, and has high robustness against noise attacks and print–scan attacks. In the case of no attacks, the watermark can be recovered without any loss. In terms of practical applications, our method can be applied in the practical leak tracing of official paper documents after distribution. [ABSTRACT FROM AUTHOR]

The development of the Internet, together with the progress of multimedia processing techniques, has led to the problems of data piracy, data tampering and illegal dissemination. Digital watermarking is an effective approach to data authentication and copyright protection. This paper proposes a geometrically robust multi-bit video watermarking algorithm based on 2-D DFT (two-dimensional discrete Fourier transform). While most of the existing video watermarking schemes require synchronization to extract the watermark from rotated or scaled videos, which is time-consuming and affects the accuracy, the proposed method can do direct extraction without performing synchronization for videos attacked by rotation, scaling or cropping. For embedding the watermark, circular templates in DFT domain are transformed into spatial masks and added to the video frames in spatial domain. A perceptual model based on local contrast is applied to keep the fidelity of the watermarked video. We also propose an accurate and efficient extraction method which is based on the cross-correlation between the Wiener-filtered DFT magnitude and the stretched template sequence in polar coordinates. Experimental results show that the proposed algorithm is robust against various kinds of attacks, such as compression, filtering, rotation, scaling, cropping, frame averaging and frame rate changing. [ABSTRACT FROM AUTHOR]

The robust watermarking scheme has very broad application scenarios. For robust watermarking methods, the transform domain based watermarking algorithms are popular. Indeed, these algorithms have strong robustness, but the visual effects may be affected. In order to balance the robustness and imperceptibility, a histogram based watermarking scheme is proposed. In this scheme, in order to enhance the robustness and imperceptibility, the low-frequency construction method (LFCM) is proposed. In LFCM, the most suitable pixels for modifications are selected by calculating the weights of pixels at different positions, and these pixels will be modified in the histogram based embedding process. After the modification, the low-frequency of the image will enhance, and the robustness of the watermarking will enhance at the same time. Experiment results show that the proposed scheme can resist compression, scaling, noise, and median blur attacks, and can resist rotation attacks to a certain extent. The proposed scheme is a non-blind watermarking scheme, and non-blind watermarking scheme is feasible when this scheme has good performance. [ABSTRACT FROM AUTHOR]

In this paper, a new blind watermarking for copyright protection of color images based on the U matrix through Quaternion Singular Value Decomposition (QSVD) is proposed. The proposed method represents the color image with a quaternion matrix, so that it can deal with the multichannel information in a holistic way. Then the array of pure quaternion is divided into non-overlapping blocks and we perform QSVD on each block to get its U matrix. The watermark is inserted into the optimally selected coefficients of the quaternion elements in the first column of the U matrix. Besides, in the procedures of watermark insertion and extraction, ensuring higher fidelity and robustness to several possible image attacks have been considered. The experimental results show that the proposed method outperforms existing schemes in terms of robustness and invisibility. [ABSTRACT FROM AUTHOR]