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The UOC is developing a technology for protecting digital content

  Foto: Unsplash/Glenn Carstens-Peters

Foto: Unsplash/Glenn Carstens-Peters

Ainhoa Sorrosal
The technique helps detect the illegal manipulation and distribution of images, audio or video and can be applied to advertising

Watermarking, using digital watermarks, is a technique that allows information to be hidden, making it imperceptible to humans, in images, videos and audio signals. David Megías, principal investigator with the K-riptography and Information Security for Open Networks (KISON) research group  at the IN3-UOC, has developed and patented it for audio and video, and is in contact with a number of international companies for its use. Among other things, watermarking enables the illegal distribution of digital content to be tracked and image manipulation to be detected. In the case of audio, the primary application is in the field of digital marketing.

These techniques can be applied to powerful markets such as audiovisual, advertising and security. The imperceptible message (watermark) is inserted coded in digital format with negligible changes to bits or certain content coefficients.

Protecting intellectual property and expanding advertising formats

In terms of the technique being developed for video, the hidden bits can be used to detect fraudulent manipulation. This way, if an unauthorized user manipulates the video images, the digital watermark will uncover it. “The technique means we can detect the mark, but it is also a reversible method because, once we have determined that the video has not been manipulated, we can retrieve the original content,” explains Megías, principal investigator with the KISON research group.  

Another possible application for watermarking is linked to the digital fingerprint. “The organizers of the Oscars send DVDs of the films to the members of the Academy with an embedded fingerprint, which is different for each person”, says Megías. “That way, they can check whether any member of the jury posts the films on the Internet or supplies the DVD to unauthorized individuals for them to redistribute”. 

In terms of audio technique, the primary application is in the field of digital marketing. “The application has been designed to work in real time and does not need an Internet connection to decode messages”, he highlights. Use in the advertising industry is clear to see. For example, it is possible that while users listen to a podcast, they can download discount coupons for a product.

More information capacity than the competition

Megías began researching the development and application of watermarking techniques 15 years ago: first audio and then video. The technology that he has developed has comparative advantages compared to other competitors. For example, the methods fostered by Megías mean that greater volumes of good-quality information can be transmitted: “We offer more capacity and maintain the imperceptibility and robustness of watermarking”, he stresses. “We are able to embed more information per second: up to 11,000 bits per second, whereas the majority of published systems vary between 50-500 bits per second”. Also, in terms of audio, it can operate in real time and extract the sound mark recorded on mobile phone microphones.  The level of distortion introduced for the mark can be adapted to different environments, depending on the needs of the application.


UOC experts

Photograph of David Megías Jiménez

David Megías Jiménez

Director of the Internet Interdisciplinary Institute (IN3)
Professor in the Faculty of Computer Science, Multimedia and Telecommunications

Expert in: Security and privacy of networks and information, and especially information hiding: watermarking, steganography and steganalysis.

Knowledge area: Security and privacy of networks and information.

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