Error Concealment Using a Halftone Watermarking Technique

In this paper, a prescription-based error concealment (PEC) method is proposed. PEC relies on pre-analyses of the concealment error image (CEI) for I-frames and the optimal error concealment scheme for P-frames at encoder side. CEI is used to enhance the image quality at decoder side after error concealment (by spatial interpolation or zero motion) of the corrupted intra-coded MBs. A set of pre-selected error concealment methods is evaluated for each corrupted inter-coded MB to determine the optimal one for the decoder. Both the CEI and the scheme indices are considered as the prescriptions for decoder and transmitted along with the video bit stream based on a reversible data embedding technique. Experiments show that the proposed method is capable of achieving PSNR improvement of up to 1.48 dB, at a considerable bit-rate, when the packet loss rate is 20%

Robust Video watermarking techniques based on DPCM Encoder and permutated DCT spectrum combined with QIM is introduced. For this purpose the pixels of incoming frames undergo permutation, followed by block wise DCT transform. The DPCM encoder generates differential spectral images. The significant coefficients of these differential spectral images are selected for embedding procedure by quantization index modulation (QIM) method. By this technique the watermark is more robust against attacks and compression. To further increase robustness and to avoid visible degradation additionally the frame order and the watermark pixels were rearranged. To extract the watermark from the video the same operations have to be done on the decoder side. The incoming video frames are permutated followed by block wise DCT transform. After the decoder builds the differential spectral image the embedded coefficients can be selected and watermark extracted by inverse QIM.

The problem of error control and concealment in video communication is becoming increasingly important because of the growing interest in video delivery over unreliable channels such as wireless networks and the Internet. This paper reviews the techniques that have been developed for error control and concealment. These techniques are described in three categories according to the roles that the encoder and decoder play in the underlying approaches. Forward error concealment includes methods that add redundancy at the source end to enhance error resilience of the coded bit streams. Error concealment by postprocessing refers to operations at the decoder to recover the damaged areas based on characteristics of image and video signals. Last, interactive error concealment covers techniques that are dependent on a dialogue between the source and destination. Both current research activities and practice in international standards are covered.

Rapid development of the digital technology and internet has made copyright protection and ownership verification of digital audio data hot research topics that have attracted a lot of interest from different parties. Since the traditional audio protection algorithms cannot solve all the problems of audio copyright protection and digital right management (DRM) due to the unique audio data features and algorithm limitations, this thesis is proposed to address the issue of audio copyright protection using watermarking techniques. Firstly, a new perception-based watermarking scheme for MPEG-4 scalable to lossless (SLS) audio is proposed. Under the control of the psychoacoustic model, the significant part of integer modified discrete cosine transform (IntMDCT) coefficients are adaptively modified during MPEG-4 SLS audio compression taking robustness, imperceptibility and security into consideration. The chaotic watermark generated by chaos is then embedded to ensure security. Moreover, the adaptive spread spectrum (SS) method is exploited to further optimize the tradeoff between robustness and transparency of this scheme. Secondly, a blind and robust audio watermarking scheme based on singular value decomposition (SVD) – followed by discrete cosine transform (DCT) with the synchronization code technique is proposed. A binary watermark is embedded into the high frequency band of the SVD-DCT block. Chaotic sequence is adopted as the synchronization code and inserted into the host signal. Thirdly, a new and robust audio watermarking scheme based on lifting wavelet transform (LWT) and SVD is proposed. Specifically, the watermark data is efficiently inserted in the low coefficient of the frequency subband of LWT audio taking advantage of both SVD and quantization index modulation (QIM). Furthermore, the synchronization code technique is also integrated in the hybrid LWT-SVD audio watermarking method. Finally, a particle swarm optimization (PSO) and SVD based audio watermarking scheme is proposed. The watermark is embedded by modifying singular values (SVs) of the host audio signal with the SS method. The designed optimization technique employs PSO to search for the optimal watermark strength by continuously adjusting the fitness values so that the conflicting requirements of robustness and imperceptibility of the watermark are satisfied optimally. Moreover, the proposed scheme has the flexibility to include or remove various watermarking attacks during training for optimization. The experimental results validate the practicality of the proposed methods and show that the proposed algorithms are very robust to typical signal manipulations. Furthermore, the results of comparison with other similar state-of-the-art audio watermarking techniques indicate that the proposed algorithms are more robust against most common signal processing attacks while preserving good imperceptibility.

We propose an error concealment method for robust video transmission based on watermarking technique. In this method, the motion vector information is used as the watermark and embedded in the transform coefficients before quantization. A proper embedding algorithm is designed with the characteristics of the video coder taken into consideration, so that the embedding watermark has little influence on the video quality and the coding efficiency. At the decoder, the extracted watermark is used to effectively detect errors and restore the corrupted motion vectors. Then the restored motion vectors are utilized in error concealment. Simulation results demonstrate the advantages of the proposed method in error prone environment. The proposed method is applicable to all the block-transform based video coding schemes.

Image watermarking techniques have continuously evolved to address new challenges and incorporate advanced features. The advent of data-driven approaches has enabled the processing and analysis of large volumes of data, extracting valuable insights and patterns. In this paper, we propose two content-aware quantization index modulation (QIM) algorithms: Content-Aware QIM (CA-QIM) and Content-Aware Minimum Distortion QIM (CAMD-QIM). These algorithms aim to improve the embedding distortion of QIM-based watermarking schemes by considering the statistics of the cover signal vectors and messages. CA-QIM introduces a canonical labeling approach, where the closest coset to each cover vector is determined during the embedding process. An adjacency matrix is constructed to capture the relationships between the cover vectors and messages. CAMD-QIM extends the concept of minimum distortion (MD) principle to content-aware QIM. Instead of quantizing the carriers to lattice points, CAMD-QIM quantizes them to close points in the correct decoding region. Canonical labeling is also employed in CAMD-QIM to enhance its performance. Both schemes can be categorized as (key-aided) semi-blind watermarking. Simulation results demonstrate the effectiveness of CA-QIM and CAMD-QIM in reducing embedding distortion compared to traditional QIM. The combination of canonical labeling and the minimum distortion principle proves to be powerful, minimizing the need for changes to most cover vectors/carriers. These content-aware QIM algorithms provide improved performance and robustness for watermarking applications.

Distributed Video Coding (DVC) is a new paradigm for video compression based on the information theoretical results of Slepian and Wolf (SW), and Wyner and Ziv (WZ). While conventional coding has a rigid complexity allocation as most of the complex tasks are performed at the encoder side, DVC enables a flexible complexity allocation between the encoder and the decoder. The most novel and interesting case is low complexity encoding and complex decoding, which is the opposite of conventional coding. While the latter is suitable for applications where the cost of the decoder is more critical than the encoder's one, DVC opens the door for a new range of applications where low complexity encoding is required and the decoder's complexity is not critical. This is interesting with the deployment of small and battery-powered multimedia mobile devices all around in our daily life. Further, since DVC operates as a reversed-complexity scheme when compared to conventional coding, DVC also enables the interesting scenario of low complexity encoding and decoding between two ends by transcoding between DVC and conventional coding. More specifically, low complexity encoding is possible by DVC at one end. Then, the resulting stream is decoded and conventionally re-encoded to enable low complexity decoding at the other end. Multiview video is attractive for a wide range of applications such as free viewpoint television, which is a system that allows viewing the scene from a viewpoint chosen by the viewer. Moreover, multiview can be beneficial for monitoring purposes in video surveillance. The increased use of multiview video systems is mainly due to the improvements in video technology and the reduced cost of cameras. While a multiview conventional codec will try to exploit the correlation among the different cameras at the encoder side, DVC allows for separate encoding of correlated video sources. Therefore, DVC requires no communication between the cameras in a multiview scenario. This is an advantage since communication is time consuming (i.e. more delay) and requires complex networking. Another appealing feature of DVC is the fact that it is based on a statistical framework. Moreover, DVC behaves as a natural joint source-channel coding solution. This results in an improved error resilience performance when compared to conventional coding. Further, DVC-based scalable codecs do not require a deterministic knowledge of the lower layers. In other words, the enhancement layers are completely independent from the base layer codec. This is called the codec-independent scalability feature, which offers a high flexibility in the way the various layers are distributed in a network. This thesis addresses the following topics: First, the theoretical foundations of DVC as well as the practical DVC scheme used in this research are presented. The potential applications for DVC are also outlined. DVC-based schemes use conventional coding to compress parts of the data, while the rest is compressed in a distributed fashion. Thus, different conventional codecs are studied in this research as they are compared in terms of compression efficiency for a rich set of sequences. This includes fine tuning the compression parameters such that the best performance is achieved for each codec. Further, DVC tools for improved Side Information (SI) and Error Concealment (EC) are introduced for monoview DVC using a partially decoded frame. The improved SI results in a significant gain in reconstruction quality for video with high activity and motion. This is done by re-estimating the erroneous motion vectors using the partially decoded frame to improve the SI quality. The latter is then used to enhance the reconstruction of the finally decoded frame. Further, the introduced spatio-temporal EC improves the quality of decoded video in the case of erroneously received packets, outperforming both spatial and temporal EC. Moreover, it also outperforms error-concealed conventional coding in different modes. Then, multiview DVC is studied in terms of SI generation, which differentiates it from the monoview case. More specifically, different multiview prediction techniques for SI generation are described and compared in terms of prediction quality, complexity and compression efficiency. Further, a technique for iterative multiview SI is introduced, where the final SI is used in an enhanced reconstruction process. The iterative SI outperforms the other SI generation techniques, especially for high motion video content. Finally, fusion techniques of temporal and inter-view side informations are introduced as well, which improves the performance of multiview DVC over monoview coding. DVC is also used to enable scalability for image and video coding. Since DVC is based on a statistical framework, the base and enhancement layers are completely independent, which is an interesting property called codec-independent scalability. Moreover, the introduced DVC scalable schemes show a good robustness to errors as the quality of decoded video steadily decreases with error rate increase. On the other hand, conventional coding exhibits a cliff effect as the performance drops dramatically after a certain error rate value. Further, the issue of privacy protection is addressed for DVC by transform domain scrambling, which is used to alter regions of interest in video such that the scene is still understood and privacy is preserved as well. The proposed scrambling techniques are shown to provide a good level of security without impairing the performance of the DVC scheme when compared to the one without scrambling. This is particularly attractive for video surveillance scenarios, which is one of the most promising applications for DVC. Finally, a practical DVC demonstrator built during this research is described, where the main requirements as well as the observed limitations are presented. Furthermore, it is defined in a setup being as close as possible to a complete real application scenario. This shows that it is actually possible to implement a complete end-to-end practical DVC system relying only on realistic assumptions. Even though DVC is inferior in terms of compression efficiency to the state of the art conventional coding for the moment, strengths of DVC reside in its good error resilience properties and the codec-independent scalability feature. Therefore, DVC offers promising possibilities for video compression with transmission over error-prone environments requirement as it significantly outperforms conventional coding in this case.

In this paper, an artificial intelligent technique for robust digital image watermarking in multiwavelet domain is proposed. The embedding technique is based on the quantization index modulation technique and the watermark extraction process does not require the original image. We have developed an optimization technique using the genetic algorithms to search for optimal quantization steps to improve the quality of watermarked image and robustness of the watermark. In addition, we construct a prediction model based on image moments and back propagation neural network to correct an attacked image geometrically before the watermark extraction process begins. The experimental results show that the proposed watermarking algorithm yields watermarked image with good imperceptibility and very robust watermark against various image processing attacks.

Error concealment at the decoder side is an economical approach to ensuring an acceptable and stable video quality in case of packet erasure or loss, and thus, it has attracted considerable research and application interest. Relevant techniques usually employ the spatial or temporal correlation to recover the motion vectors (MVs) of the missing blocks, and interpolation, extrapolation, or boundary-matching schemes are usually effective. However, for heavily corrupted sequences, e.g., with block loss rate beyond 50 %, most methods might perform less satisfactorily. Inspired by the tracking efficiency of Kalman filter (KF), in the present work, we adopted it to predict the missing MVs, and the unpredicted ones (minority) were restored complementarily using a modified bilinear motion field interpolation (MFI) method. Since the KF prediction is independent of the loss rate, the present framework proves to be robust for heavily corrupted videos. Experimental results on typical sequences reveal that the proposed algorithm outperforms the boundary-matching algorithm embedded in the H.264/AVC reference code, the MFI and the MV extrapolation techniques in the literature.

Error concealment at the decoder side is an economical approach to ensuring an acceptable and stable video quality in case of packet erasure or loss, and thus attracts lots of interest. Current techniques mainly employ the spatial or temporal correlation to predict the motion vectors of the missing blocks, and interpolation, extrapolation or boundary matching schemes are usually effective. However, for heavily corrupted sequences, e.g., with macroblock loss rate beyond 50%, most methods might perform less satisfactorily. Inspired by the tracking efficiency of Kalman filter, in the present work, we adopted it to predict the missing MVs, and the unpredicted ones (minority) were recovered complementarily by using the bilinear motion field interpolation (MFI) method. The experimental results on typical sequences reveal that the proposed algorithm outperforms the boundary matching algorithm and the MFI technique by up to about 4.77 dB and 3.66 dB respectively for heavily corrupted videos.

In this paper, a type of multilevel Quantization Index Modulation (QIM) algorithms is proposed by adopting the concept of multilevel nested lattice coding. We first introduce the multilevel scalar-QIM and then extend it to the vector case by using lattice-QIM. The lattice definition and nested lattices construction are specified such that the constructed nested lattices is suitable for multilevel lattice-QIM. The proposed scheme embeds multiple watermark sequences into the same host signal via several embedding rounds. Each round of embedding uses quantizers of different radii, and thus provides different robustness. As a result, the embedded watermark sequences can be used for various purposes. Benefiting from the scalable robustness and adjustable embedding rate, the proposed multilevel QIM presents good performances and supports a wide range of applications.

Purpose – The purpose of this paper is to solve the pack loss problem of video transmitted over error‐prone channels. Pack loss generally affects the visual quality of reconstructed frames significantly. Consequently, a grey approach to error concealment (EC) is proposed.Design/methodology/approach – Note that missing information in error blocks can be found before and after the error frame. Thus, two adjacent error‐free frames are utilized to conceal error blocks caused by packet loss. This paper presents an EC approach based on grey polynomial interpolation (GPI) which is called the GTEC. In the GTEC, the following stages are involved. First, error blocks due to packed loss are detected. Then, optimal reference blocks in adjacent frames are found through boundary matching algorithm (BMA). Finally, estimated blocks are obtained by the GPI. By replacing error blocks with the estimated blocks, EC is completed in the GTEC.Findings – In the simulation, the proposed GTEC is compared with the EC scheme in H.26...

In this paper, we present a framework for detecting tampered information in digital videos. Using the proposed technique is possible to detect several types of tampering with a pixel granularity. The framework uses a combination of temporal and spatial watermarks that do not decrease the perceived quality of the host videos. We use a modified version of Quantization Index Modulation (QIM) algorithm to store the watermarks. Since QIM is a fragile watermarking scheme, it is possible to detect local, global, and temporal tampers and also estimate the attack type. The framework is fast, robust, and accurate.

To protect the copyright for providing ownership in audio signal watermarking techniques are requisite. In this paper, a new robust audio watermarking algorithm is proposed, which is based on Schur decomposition and Dither modulation. In the Schur decomposition and Dither modulation based technique, watermark embedding is done using Dither modulation quantization which has a good performance in terms of imperceptibility, robustness and speed etc. Schur decomposition and Dither modulation is a blind audio watermarking technique which is robust against various attacks such as Additive White Gaussian Noise (AWGN), cropping, echoing, low pass filtering, requantization, resampling etc. The proposed technique has shown efficient and stable performance against various attacks and it is computationally faster.

DC coefficient based watermarking schemes are known for good robustness against common image processing operations. This paper use scheme based on Quantization Index Modulation (QIM) in which both DC and AC coefficients are quantized for watermark embedding. The purpose is to increase the embedding capacity while maintaining constant robustness. Step size of quantizer decides robustness in QIM based methods. For this work, step size is decided based on the frequency content of an image. It results in increased robustness for fixed capacity or vice versa.