---DIGITAL WATERMARKING---
What is it?
Digital watermarking is an adaptation of the commonly used and well known paper watermarks to the digital world. Digital watermarking describes methods and technologies that allow to hide information, for example a number or text, in digital media, such as images, video and audio. The embedding takes place by manipulating the content of the digital data, that means the information is not embedded in the frame around the data. The hiding process has to be such that the modifications of the media are imperceptible. For images this means that the modifications of the pixel values have to be invisible. Furthermore, the watermark has to be robust or fragile, depending on the application. With robustness we refer to the capability of the watermark to resist to manipulations of the media, such as lossy compression, scaling, and cropping, just to enumerate some. Fragility means that the watermark should not resist tampering, or only up to a certain extent.
What can it be used for?
First applications which came to mind were related to copyright protection of digital media. In the past duplicating art work was quite complicated and required a great expertise for that the counterfeit looked like the original. However, in the digital world this is not true. For everyone it is extremely easy to duplicate digital data and this even without any loss of quality. Similar to the process in which artist artistically signed their paintings with a brush to claim their copyrights, artists of today can watermark their work and hide for example their name in the image. Hence, the embedded watermark will allow to identify the owner of the work. It is clear that this concept is also applicable to other media such as digital video and audio. Especially the distribution of digital audio over the Internet in the MP3 format is currently a big problem. In this scenario digital watermarking may be useful to set up a controlled audio distribution and provide efficient means for copyright protection, usually in collaboration with international registration bodies such as the IDDN-Inter Deposit Digital Number.
Are there any other applications?
There is a number of possible applications for digital watermarking technologies and this number is increasing rapidly. For example, in the field of data security, watermarks may be used for certification, authentication, and conditional access. Certification is an important issues for official documents, such as identity cards or passports.
Digital watermarking allows to mutually link information on the documents. That means that some information is written twice on the document: for instance, the name of a passport owner is normally printed in clear text and is also hidden as an invisible watermark in the photo of the owner. If anyone would intend to counterfeit the passport by replacing the photo, it would be possible to detect the change by scanning the passport and verifying the name hidden in the photo does not match any more the name printed on the passport. The picture below shows a printing machine from Intercard for various types of plastic cards.
Another application is the authentication of image content. The goal of this application is to detect alterations and modifications in an image. The three pictures below illustrate an example of this application. The picture on the left shows an original photo of a car that has been protected with a watermarking technology. In the center, the same picture is shown but with a small modification: the numbers on the license plate have been changed. The picture on the right shows the photo after running the watermark detection program on the tampered photo. The tampered areas are indicated in white and we can clearly see that the detected areas corresponds to the modifications applied to the original photo.
Using digital watermarks for integrity verification. The protected image is on the left. A modified image is obtained by swapping the numbers 9 and 4. Watermarking technology allows to detect and highlights the modified areas, as shown on the right.
Other applications related to conditional access and copy-control are also possible. For example conditional access to confidential data on CD-roms may be provided using digital watermarking technology. The concept consists of inserting a watermark into the CD label. In order to read and decrypt the data stored on the CD, the watermark has to be read since it contains information needed for decryption. If someone copies the CD, he will not be able to read the data in clear-text since he does not have the required watermark. The picture below shows an example of a protected CD. To read the data on the CD, the user starts a program on the CD. This program asks the user to put the CD on the scanner and then reads the watermark. If the watermark is valid the program decrypts the data on the CD and gives the user access the the clear-text data. (patent pending, contact us for licence.)
Conditional access to confidential data stored on CD-roms.
A different application is related to copy-control. Several companies work on a watermarking system for copy control in the DVD environment. Fully functioning solutions exist already, however, for the moment they have not been entirely approved by the content producers and providers. Finally, this solution is also an efficient and simple way to prevent the use of illegal copies of a software. It has a similar functionaly as the anti-piracy device called "dongle", but is more compact (you can loose a dongle) and less expensive.
Beside applications in the fields of copyright protection, authentication and security, digital watermarks can also serve as invisible labels and content links. For example, photo development laboratories may insert a watermark into the picture to link the print to its negative. This way is very simple to find the negative for a given print. All one has to do is scan the print and extracted the information about the negative. In a completely different scenario digital watermarks may be used as a geometrical reference which may be useful for programs such as optical character recognition (OCR) software. The embedded calibration watermark may improve the detection reliability of the OCR software since it allows the determination of translation, rotation, and scaling.
Where is the future?
An exhaustive list of watermarking applications is of course impossible. However, it is interesting to note the increasing interest in fragile watermarking technologies. Especially applications related to copy protection of printed media are very promising. Examples here include the protection of bills with digital watermarks. Various companies have projects in this direction and it is very likely that fully functioning solutions will soon be available.
In addition to technological developments, marketing and business issues are extremely important and require in-depth analysis and strategic planing. It is very important to prepare the industry to the usage of digital watermarks and to convince them of the added value their products can gain if they employ digital watermarking technologies.
alpvision.com
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Public company that does watermarking: NASDAQ:DMRC
Digimarc Corporation is a provider of patented digital watermarking technologies that allow an imperceptible digital code to be embedded in the printed or digital versions of media content, such as commercial and consumer photographs, movies, music, magazine advertisements, catalogs, product packages, and valuable documents, including financial instruments, passports and event tickets. The Company's products are grouped along three lines of business: Secure Documents, Media Commerce and Digimarc MediaBridge. Each product line offers systems generally including embedder software, which is used to place Digimarc's digital watermarks into content, and reader technology, which is incorporated into digital devices to detect, read and respond to the embedded code.
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