Maurice Maes

Video watermarking system for broadcast monitoring

This paper presents a video watermarking technology for broadcast monitoring. The technology has been developed at the Philips Research Laboratories in Eindhoven in the context of the European ESPRIT project VIVA (Visual Identity Verification Auditor). The aim of the VIVA project is to investigate and demonstrate a professional broadcast surveillance system. The key technology in the VIVA project is a new video watermarking technique by the name of JAWS (Just Another Watermarking System). The JAWS system has been developed such that the embedded watermarks (1) are invisible, (2) are robust with respect to all common processing steps in the broadcast transmission chain, (3) have a very low probability of false alarms, (4) have a large payload at high rate, and (5) allow for a low complexity and a real-time detection. In this paper we present the basic ingredients of the JAWS technology. We also briefly discuss the performance of JAWS with respect to the requirements of broadcast monitoring.

On a cyclic string-to-string correction problem

We present an O(nm log m) algorithm to solve the string-to-string correction problem for cyclic strings.

Digital watermarking for DVD video copy protection

We illustrate the various issues that play a role in designing a copy-protection system for digital versatile disk (DVD) video as perceived by Millennium, one of the two contenders in the DVD-video copy-protection standardization activity. We present the Millennium watermark system, the systems proposed for DVD video copy protection by Philips, Macrovision, and Digimarc. We also address some specific system aspects, such as watermark detector location and copy generation control.

Polygonal shape recognition using string-matching techniques

In this paper we study several aspects of the use of string-matching techniques as an approach to the problem of recognizing and classifying polygons. Several authors have already proposed methods for polygon recognition that are based on string-matching. In many cases, however, linear strings are used to represent polygons, which makes it difficult to handle different orientations of an object efficiently. We can, however, easily extend the linear string-matching techniques to cyclic strings, at some small computational cost. We will propose a method to represent polygons as cyclic strings and we will show how cyclic string-matching techniques can be used for rotation-, translation- and scale-independent polygonal shape recognition. We will, however, also point out the limitations of such an approach.

The VIVA project: digital watermarking for broadcast monitoring

The main objective of the VIVA project (Visual Identity Verification Auditor) is to investigate and demonstrate a professional broadcast surveillance system. Broadcast material is pre-encoded with an invisible and unique watermark identifier. By automatically monitoring television broadcasts and registering which assets have been pre-encoded, a mechanism for IPR protection is provided. The applications of such a system include copyright protection and proof of ownership, verification of commercial transmissions, assessment of sponsorship effectiveness, protection against illegal transmission, statistical data collection and analysis of broadcast content. The watermarking technology is optimised for the high picture quality needed in a broadcast environment. At the same time, the watermark survives signal processing operations which routinely occur in broadcasting systems such as digital to analogue conversion, editing and compression. The monitoring system detects a 36-bit payload every second, which guarantees an operation time of more than 13 years, without recourse to repeat identifiers. The detection algorithm has reasonably low complexity, enabling real time watermark detection for many broadcast channels simultaneously. We report on the first results of a field trial, using a satellite link between Sweden and Belgium, proving the feasibility of the system.

Digital watermarking by geometric warping

A new method is presented for watermarking digital images and video streams. This technique embeds information in an image by changing the geometric features of the image. The method is essentially different from existing techniques in which a pseudo-noise pattern is added to the image. The new method has the advantage that the detection is computationally faster than existing methods. Furthermore, it is easier to detect the watermark in images that have been rotated, scaled, or distorted by a geometric transformation. The watermark is formed by a predefined dense pixel pattern, such as a collection of lines. Salient points in an image are warped into the vicinity of the line pattern in such a way that the changes to the image are imperceptible.

Exploiting shift invariance to obtain a high payload in digital image watermarking

Robust, invisible watermarking of digital images or video very often has to satisfy a set of mutually conflicting requirements. These requirements include invisibility, robustness to image processing and geometric transformations, low false positive probabilities, high payload, fast detection and embedding, etc. In this paper we show how invariance to translations can be exploited to increase the payload. This is achieved by simultaneous embedding of several shifted watermark patterns, such that the information content is hidden in the relative shifts of the patterns. The principles of this are illustrated for the case of JAWS, a spatial domain watermark method developed by Philips. The method can easily be applied to other watermark methods which are able to detect shifted versions of watermarks.

Twin peaks : The histogram attack to fixed depth image watermarks

In this paper we present an attack to fixed depth image watermarks. The attack is based on histogram analysis of a watermarked image. With this attack, the watermark can often be reconstructed from just a few images, without using the detector.

Performance measurements of a real-time digital watermarking system for broadcast monitoring

At present it is very easy to distribute and copy multimedia content. Digital watermarking is a technical solution to the copyright problem. In its basic form a digital watermark is a small signal added to a multimedia asset and carrying sufficient data to provide IPR (Intellectual Properly Right) protection. In the European Esprit project VIVA (Visual Identity Verification Auditor) this digital watermarking technology is used to investigate, design and demonstrate a professional broadcast surveillance system. A real-time digital watermark embedder and detector for broadcast monitoring are implemented in software on a powerful DSP (digital signal processor). In this paper a short overview of the watermarking algorithms and their implementation is given. Measurements are done in a laboratory environment under real-time conditions and are very convincing. The experimental results reveal that the watermark can survive much common processing in the broadcast chain.

How to achieve robustness against scaling in a real-time digital watermarking system for broadcast monitoring

In the European Esprit project VIVA (Visual Identity Verification Auditor) a real-time digital watermarking system for broadcast monitoring has been investigated and implemented. On top of the usual requirements for watermarks, the VIVA watermarking system has to satisfy an additional number of constraints. One of the most important constraints in a broadcast environment is the robustness of the watermark against scaling. This paper describes how robustness against scaling is achieved in the VIVA project. Furthermore, a real-time implementation of the algorithms is discussed. Experimental results prove the effectiveness of the algorithms.