Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Holograms detect digital fraud

22.06.2005


A new technique for detecting forged photographs will help newspapers and magazines check celebrity pictures that might have been doctored to make them more newsworthy, and prevent hackers from tampering with sensitive legal images including fingerprint records and medical scans used as evidence in court.



Defence agencies could also use the technique to verify the source of secret military reports, and to protect satellite images, such as aerial photographs of the Iraqi desert, from manipulation.

Developed by physicists Professor Giuseppe Schirripa Spagnolo, Carla Simonetti and Lorenzo Cozzella from the University of Roma Tre in Rome, Italy, this research was published today (21st June 2005) in the latest issue of the Institute of Physics journal, Journal of Optics A.


In their system, an image, e.g. a company logo, is added to a digital photograph as an invisible "watermark". Any subsequent attempt to alter the content of the photograph also results in damage to the watermark. Forgery can then be detected by using a computer to extract the watermark and check it for damage. In a forged picture, it can even identify the object or section which has been tampered with.

The team had to ensure that only an authorised recipient can extract the watermark, which could otherwise be added to a fraudulent image to pass it off as genuine. To counter this problem the watermark is encrypted before adding it to the image, so that only someone who knows the private key can reconstruct it. Furthermore, the encryption makes it difficult to detect whether an image has been watermarked or not.

Before it is added to the photograph the encrypted mark is turned into a computer generated hologram (CGH). This is a simulation of the pattern of light waves that is recorded when a real hologram is made. As with all holograms, a small part of the CGH contains enough information to recreate the entire image. This means that only a small part of the watermarked image is needed to extract the watermark.

When the CGH is added to the image it replaces the image "noise", which has been filtered out beforehand. Noise is random, high-frequency information that doesn¡¦t contribute to the image that you see, and can be removed without damaging the picture. The CGH watermark information is in the same high-frequency band as the noise, so it is invisible to the human eye when added to the photograph.

The watermark is now embedded in the digital image file, in a separate part of the spectrum to the picture information, making it easy for the recipient to isolate and extract it. If the watermark can’t be reconstructed using the private key it means that someone has destroyed the watermark by trying to modify the image.

Testing their technique, the team demonstrated how a hologram watermark can be used to find out which part of an image has been tampered with. They changed colours in certain areas of a watermarked image and divided it into 16 parts, extracting a watermark from each. The parts where the colour change had taken place showed a significantly damaged watermark indicating that they had been modified.

"We hope that this technique can be used to improve the reliability of photographs in the media" said Dr Lorenzo Cozella, co-author of the paper, "Digital cameras could be developed so that an invisible watermark is added when a picture is taken. A newspaper buying a photo from a freelancer could then check for a watermark to confirm that it hasn¡¦t been tampered with to make it more newsworthy."

The system could also protect databases of images that serve as evidence in court, for example fingerprint records or medical scans, which could be used in cases of alleged malpractice. All images in the database would be watermarked so they could be checked without having to refer to the original hard-copy. This would be especially useful for electronically stored information exposed to external users via the internet, increasing its vulnerability to fraud.

David Reid | EurekAlert!
Further information:
http://www.iop.org

More articles from Health and Medicine:

nachricht Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>