In the context of stereo video, disparity-coherent watermarking has been introduced to provide superior robustness against virtual view synthesis, as well as to improve perceived fidelity. Still, a number of practical considerations have been overlooked and in particular the role of the underlying depth estimation tool on performances. In this article, we explore the interplay between various stereo video processing primitives and highlight a few take away lessons that should be accounted for to improve performances of future disparity-coherent watermarking systems. In particular, we highlight how lost correspondences during the stereo warping process impact watermark detection, thereby calling for innovative designs.
Stereo video content calls for new watermarking strategies, e.g. to achieve robustness against virtual view synthesis. Prior works focused either on inserting the watermark in an invariant domain or on guaranteeing that the watermarks introduced in the left and right views are coherent with the disparity of the scene. However, the first approach raises fidelity issues while the second requires side information at detection i.e. the detector is not blind. In this paper, we propose a new blind detection procedure for disparity-coherent watermarks. In a nutshell, the detector relies on cross-correlation to aggregate the scattered pieces of the embedded reference watermark pattern rather than warping the reference pattern according to the parameters of the current view prior to detection. Reported experimental results indicate that this revisited detector successfully manages to retrieve embedded watermarks even after lossy compression.
A number of technologies claim to be robust against content re-acquisition with a camera recorder e.g. water- marking and content ngerprinting. However, the benchmarking campaigns required to evaluate the impact of the camcorder path are tedious and such evaluation is routinely overlooked in practice. Due to the interaction between numerous devices, camcording displayed content modi es the video essence in various ways, including geometric distortions, temporal transforms, non-uniform and varying luminance transformations, saturation, color alteration, etc. It is necessary to clearly understand the di erent phenomena at stake in order to design ef- cient countermeasures or to build accurate simulators which mimic these e ects. As a rst step in this direction, we focus in this study solely on luminance transforms. In particular, we investigate three di erent alterations, namely: (i) the spatial non uniformity, (ii) the steady state luminance response, and (iii) the transient luminance response.
This paper presents an approach to evaluate the acoustic path transmission of watermarked audio tracks through
large scale simulations. The multitude of signal alterations performed implicitly via acoustic path transmission
are aggregated through the measurement of impulse responses. These impulse responses are integrated in a
test suite in order to be able to perform large scale automated tests as a replacement of the time intensive
and expensive individual measurements. The reliability of the approach is demonstrated by the comparison of
measurements and simulations.
Digital camcording in the premises of cinema theaters is the main source of pirate copies of newly released
movies. To trace such recordings, watermarking systems are exploited in order for each projection to be unique
and thus identifiable. The forensic analysis to recover these marks is different for digital and legacy cinemas. To
avoid running both detectors, a reliable oracle discriminating between cams originating from analog or digital
projections is required. This article details a classification framework relying on three complementary features :
the spatial uniformity of the screen illumination, the vertical (in)stability of the projected image, and the luminance
artifacts due to the interplay between the display and acquisition devices. The system has been tuned
with cams captured in a controlled environment and benchmarked against a medium-sized dataset (61 samples)
composed of real-life pirate cams. Reported experimental results demonstrate that such a framework yields over
80% classification accuracy.
Re-quantization commonly occurs when digital multimedia content is being tampered with. Detecting requantization
is therefore an important element for assessing the authenticity of digital multimedia content.
In this paper, we introduce three features based on the observation that re-quantization (i) induces periodic
artifacts and (ii) introduces discontinuities in the signal histogram. After validating the discriminative potential
of these features with synthetic signals, we propose a system to detect JPEG re-compression. Both linear (FLD)
and non-linear (SVM) classifications are investigated. Experimental results clearly demonstrate the ability of the
proposed features to detect JPEG re-compression, as well as their competitiveness compared to prior approaches
to achieve the same goal.
Lattice codes and quantization-based techniques have received considerable attention as a method of digital watermarking
with side information. However, these algorithms are also recognized to be highly sensitive to common
signal processing primitives such as valuemetric scaling, e.g. changes in volume of a song, or re-quantization,
e.g. JPEG compression. Hence, it is reasonable to investigate alternative codes which may offer the potential
for superior performance. In previous work, we designed a new class of codes, called dirty paper trellis codes
(DPTC), which are by construction immune to valuemetric scaling. Although DPTC have shown themselves to
be resistant to certain classes attacks, the trellises were generated randomly, thus leading to suboptimal codes.
In this paper, Ungerboeck's work on trellis coded modulation (TCM) is exploited to significantly improve the
performance of the DPTC. Experimental results show that the resulting trellises significantly outperform the
Digital watermarking has first been introduced as a possible way to ensure intellectual property (IP) protection. However, fifteen years after its infancy, it is still considered as a young technology and digital watermarking is far from being introduced in Digital Right Management (DRM) frameworks. A possible explanation is that the research community has so far mainly focused on the robustness of the embedded watermark and has almost ignored security aspects. For IP protection applications such as fingerprinting and copyright protection, the watermark should provide means to ensure some kind of trust in a non secure environment. To this end, security against attacks from malicious users has to be considered. This paper will focus on collusion attacks to evaluate security in the context of video watermarking. In particular, security pitfalls will be exhibited when frame-by frame embedding strategies are enforced for video watermarking. Two alternative strategies will be surveyed: either eavesdropping the watermarking channel to identify some redundant hidden structure, or jamming the watermarking channel to wash out the embedded watermark signal. Finally, the need for a new brand of watermarking schemes will be highlighted if the watermark is to be released in a hostile environment, which is typically the case for IP protection applications.
Digital watermarking was introduced during the last decade as a complementary technology to protect digital multimedia data. Watermarking digital video material has already been studied, but it is still usually regarded as watermarking a sequence of still images. However, it is well-known that such straightforward frame-by-frame approaches result in low performance in terms of security. In particular, basic intra-video collusion attacks can easily defeat basic embedding strategies. In this paper, an extension of the simple temporal frame averaging attack will be presented, which basically considers frame registration to enlarge the averaging temporal window size. With this attack in mind, video processing, especially video mosaicing, will be considered to produce a temporally coherent watermark. In other words, an embedding strategy will be proposed which ensures that all the projections of a given 3D point in a movie set carry the same watermark sample along a video scene. Finally, there will be a discussion regarding the impact of this novel embedding strategy on different relevant parameters in digital watermarking e.g. capacity, visibility, robustness and security.