In this paper we present an extension to the video watermarking scheme that we introduced in our previous
work as well as a new objective quality metric for video watermarks. As the amount of data that today's
video watermarks can embed into a single video frame still is too small for many practical applications, our
watermarking scheme provides a method for splitting the watermark message and spreading it over the complete
video. This way we were able to overcome the capacity limitations, but we also encountered a new kind of
distortions that effects the visual quality of the video watermark, the so-called "flickering" effect. However we
found that the existing video quality metrics were unable to capture the "flickering" effect. The extension of our
watermarking scheme that is presented in this paper is able to reduce the "flickering" effect and thus improves
the visual quality of the video watermark by using scene detection techniques. Further on we introduce a new
quality metric for measuring the "flickering" effect, which is based on the well-known SSIM metric for still images
and which we call "Double SSIM Difference". Finally we present our results of the evaluation of the proposed
extension of the watermark embedding process, which was applied using the "Double SSIM Difference" metric.
Semi-fragile video watermarking is a technology for detecting manipulations. It provides robustness against
content-preserving manipulations as well as sensitivity to
content-changing manipulations. To achieve this,
robust content-describing features are applied. We use the SIFT keypoint detection as feature for our semifragile
video watermarking scheme introduced in this work. SIFT (Scale Invariant Feature Transformation)
detects points invariant to image scale and rotation and can be used for object matching after changing the 3D
viewpoint, addition of noise and modifications in illumination. With the detected feature points we generate
an authentication message, which is embedded with a robust video watermark. In the verification process we
introduce a temporal filtering approach to reduce the distortions caused by content-preserving manipulations.
We present experimental results demonstrating the robustness and sensitivity of our scheme.
Changing the distribution channel of movies from analogue to digital provides new perspectives and possibilities for
applying digital watermarking as security mechanisms. Digital watermarking provides its best security options when
used for individual marking of copies to trace back distribution leaks. For analogue copies, protecting movies with
individual watermarks was only cost-effective for small sets of copies as in promotional copies as duplication is done in
an automated photo-optical way. Modifications of the analogue copies only provide relatively crude approaches of
individual marking. Digital copies on the other hand can easily be modified before, during or even after distribution to
cinemas. It is also possible to embed watermarks at all of these stages to secure the complete distribution chain from
studio to cinema. In our paper we discuss two watermarking strategies suitable for different applications in the digital
cinema domain, video and still image watermarking. We provide technical background and also discuss the interference
of applying both algorithms at the same time.
In our paper we discuss and compare the possibilities and shortcomings of both content-fragile watermarking and
digital forensics and analyze if the combination of both techniques allows the identification of more than the sum
of all manipulations identified by both techniques on their own due to synergetic effects. The first part of the
paper discusses the theoretical possibilities offered by a combined approach, in which forensics and watermarking
are considered as complementary tools for data authentication or deeply combined together, in order to reduce
their error rate and to enhance the detection efficiency. After this conceptual discussion the paper proposes
some concrete examples in which the joint approach is applied to video authentication. Some specific forensics
techniques are analyzed and expanded to handle efficiently video data. The examples show possible extensions
of passive-blind image forgery detection to video data, where the motion and time related characteristics of video
are efficiently exploited.
There are several scenarios where the integrity of digital images and videos has to be verified. Examples can be found in videos captured by surveillance cameras. In this paper we propose a semi-fragile watermarking scheme, which can be applied on still images as well as on digital videos. We concentrate on the protection of I-frames in compressed MPEG-1/2 videos. We use the entropy of the probability distribution of gray level values in block groups to generate a binary feature mask, which is embedded robustly into an adjacent I-frame. The approach can distinguish between content-preserving and content-changing manipulations. Positions of content-changing manipulations can be localized. We provide experimental results to analyze the effectiveness of the scheme. In the evaluation part we concentrate on the robustness against content-preserving and the sensitivity to content-changing manipulations.
In this article we present a semi-fragile watermarking scheme for authenticating intra-coded frames in compressed digital videos. The scheme provides the detection of content-changing manipulations while being moderately robust against content-preserving manipulations. More generally, we mean by content-preserving manipulations those, which are applied in post-production processes, such as compression. Content-changing manipulations remove or insert objects into frames or sequences of frames. We focus in this work on a semi-fragile watermarking method based on invariant features referred to as points of interests. The features are extracted using the Moravec-Operator. The interest point operator of Moravec is totally un-supervised and does not require any a priori knowledge in the class of objects being protected in a given frame. Out of the interest points we generate a binary mask, which will be embedded robustly as watermark into the video. In the verification process we compare the detected watermark with the points of interest from the video, which has to be verified. We present test results evaluating the robustness against content-preserving manipulations and the fragility regarding content-changing manipulations. Beside the discussion of the results we propose a procedure to provide security of the scheme against forgery attacks.
This paper presents a new content-fragile watermarking algorithm for the detection and localization of malicious manipulations of MPEG-I/II videos. While being fragile to malicious manipulations, the watermarking scheme is robust against content-preserving manipulations like re-encoding processes. It is a bitstream watermarking method based on 8x8 DCT blocks. One of the main advantages of our scheme is the possibility of localizing positions within the video where modifications occurred. Another main advantage is the portability of the scheme to other multimedia documents based on the 8x8 DCT block domain, e.g. JPEG images. The framework of the watermarking scheme can be divided into three main parts: watermark construction, watermark embedding and watermark detection. We derive a Content Based Message (CBM) from the multimedia document, based on a partial energy relationship between two groups of DCT blocks. Embedding the CBM is based on the Differential Energy Watermarking (DEW) concept. In the detection process we compare the CBM and the retrieved watermark to detect and locate manipulations. Besides the algorithm we present experimental results to demonstrate the feasibility of the scheme. We discuss four experiments representing four typical kinds of malicious manipulations.
A main problem of I-frame based watermarking schemes is their lack of robustness regarding re-encoding attacks on
MPEG material. After a normal post-processing modification the structure of the Groups of Pictures (GOPs) in the
modified video should be the same as in the original one. An attack, which has the goal to destroy the watermark, could
change this structure. The position of the marked intra coded frames will be shifted. Without detecting the correct frame
position an incorrect watermark message could be retrieved. Our conceptual paper proposes a possible solution. A
combined watermark, consisting of two watermark messages, is embedded into the video material to increase the
robustness of the watermark. The first part of the message is the synchronization information to locate the previously
marked frames. The second part contains the information watermark. Our approach is to design a template pattern based
on the synchronization information. With the pattern the original I-frame can be detected and the correct watermark
information can be retrieved. After the recovery of the attacked video material the watermark can be correctly retrieved.
We present the concept and the evaluation of the first test results.
MPEG-4 is an international object-based standard that provides technological basis for digital television, interactive graphics and multimedia applications. These objects can be natural or synthetic e.g. textures, 3D objects, videos or sounds. In this paper we suggest an integrity approach to protect the content of MPEG-4 data. The essential part of this approach is to embed a robust watermark into each visual, audio and 3D object. The content fragile watermark verifying the integrity of a scene is the sum of all information retrieved from the robust watermarks extracted from the objects of the scene. The information of the fragile watermark will be distributed redundantly to all robust watermarks of the scene. Another essential part of our approach is to embed a part of the scene description or object descriptors as a watermark message into the video or audio streams. The amount of embedded information depends on the payload of the watermarking algorithms. We also analyze the possibility of embedding equivalent information into 3D models, depending on the application.