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3D image watermarking for protecting micro-CT data exchange

23 Sep 2013, 15:10

2h 20m

Necsa's Visitor Centre

Poster Presentation Poster Posters, Exhibition and Necsa Visit

Speaker

Dr Gérard Subsol (LIRMM-CNRS, France)

Description

In the context of microfocus X-ray imaging of fossils that constitutes an important part of the heritage in a country, more and more digital 3D images are being sent over computer networks. Institutions curating fossil collections attribute legal and ethical weight to these data; acknowledging their own rights and thereby willing to ensure the protection of data in their possession. From a practical and technical point of view, it is often important to achieve : (1) the confidentiality of the data, by restricting access to the rightful owners ; (2) the integrity of the data, ensuring that the information has not been, and will not be, modified by anyone; (3) the availability, which guarantees access to the data within standard procedure to persons in agreed conditions. An important issue is then to trace digital 3D images along the chain from their acquisition to their scientific investigation. Watermarking algorithms provide traceability by embedding a message directly into the 3D image in a quasi-invisible way. The very small difference between the original image and its watermarked version corresponds to the watermark signal associated with the embedded message. Of course, care must be taken to ensure that the watermarked 3D image has the same value as the original one. Watermarking involves in general the insertion of a code identifying the owner but it is also possible to insert a trace linked to the user. Several cases making use of watermarking can be identified : - the authenticity of images with the insertion of data confirming the origin and the fact that a certain 3D image refers to a particular fossil and institution ; - controlling the integrity of 3D images, by putting control information, such as a digital signature, within data ; - the addition of meta-data, allowing the content of images to be enriched by attaching a semantic description of the content. Watermarking techniques are numerous and but they share some characteristics which, depending on the application, should be kept in mind when choosing the appropriate technique: robustness, capacity, complexity and invisibility. We will present preliminary experiments on micro-CT images of anatomical structures and fossils.