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With a growing interest in culture and related entities, several issues around intellectual property and ownership of culture and cultural artifacts arise. When these artifacts are digitized, the issues, in many cases, become more acute. With the growing interest, new markets must be developed to exploit this opportunity. Due to the nature of culture, this can also not be done on a purely commercial basis. Issues like access from educational and awareness programs must be addressed for both the real and digital world. A large number of issues need to be addressed on an international basis before trade in digital cultureware can be done painlessly. In this paper we discuss some of the non-technical issues relating to the establishment and use of digitally captured cultureware repositories. We also propose a method of ownership identification through the use of digital watermarks. This method is evaluated in a number of application domains in terms of applicability and robustness.
Culture is receiving an increasing level of attention globally. The realization that culture presents enormous commercial and educational value gave rise to several initiatives that aim to leverage this value. There is also an increasing need, for various reasons, to preserve cultural heritage. Although a number of debates exist on the validity and merits of digital cultureware, this paper will not try to address these issues.
The creation of digital culture repositories is one of the methods of preserving culture and leveraging the commercial and educational value of culture. Technologies such as multimedia and the Internet provide rich mechanisms to create and distribute digital cultural entities (or cultureware). One of the fundamental issues with digital cultural repositories is the tension between access and intellectual property protection. Fundamentally, this is not a technical question. The issue has many dimensions, including:
With the advent of digital technologies and communications the lossless reproduction and distribution of valuable digital media has become a reality. The ease of perfect reproduction and distribution of the reproduced digital media has created problems for content creators as far as Proof of Ownership and Copyright Protection are concerned. In conjunction with the above, digital media is very susceptible to unauthorized modification before distribution, which has serious implications for the credibility of the original content creator. This, in turn, has serious implications for the development of a market in digital cultureware.
In order to develop appropriate Intellectual Property Protection mechanisms for digital cultureware, one must understand the players and the rules of the game in the digital cultureware marketplace. In its nature, this is a very complicated area and cannot be dealt with sufficiently within the scope of the paper.
The digital cultureware arena has a large number of role players. It is also difficult to group the players, because of the lack of clear boundaries between functions in the digital domain. The traditional roles such as Author, Publisher, Distributor and Consumer can successfully be applied in this domain. There are areas where the distinction becomes fuzzy, especially when one considers the argument that culture exists or existed in a community and is therefore "authored" by living it.
The rules of the game in the digital cultureware marketplace are ill-defined at best. Existing copy protection laws might address most of the intellectual property rights in this domain. The argument used most of the time says that digital cultureware should be treated the same as other multimedia products such as games. There are, however, a few areas of concern in the cultureware domain, such as:
From some of the issues discussed above, combined with the need for market development, one can articulate a number of "needs" and realities for digital cultureware intellectual property protection.
In essence, no new rules are needed, but one must be aware of the differences. Any IPR protection scheme must be flexible enough to account for the differences between jurisdictions. One would therefore probably opt for simplicity that will satisfy very specific requirements and not attempt an all-encompassing solution.
In this light, we explored the use of digital watermarks to provide a technical method for identification that can be used in ownership establishment.
A digital watermark is the process of embedding a robust and secure message (either visible or invisible) directly into the digital media. The embedded message (digital watermark) can typically contain information regarding the ownership, copyright, timestamps and the legitimate receiver of the digital media.
In the following section we present an overview of digital watermarking as well as requirements to successfully embed a digital watermark in digital media. This is followed by sections describing current approaches and limitations. Our final section contains our conclusion regarding the usage of digital watermarking in a digital archive context.
Digital watermarking is the process of embedding a robust, secure message with a low degree of obtrusiveness into the media content.
Robustness implies that the watermark is difficult to remove or modify unless the digital media is altered to the point of no value.
A watermark scheme is regarded as secure if unauthorized parties cannot erase or modify the embedded watermark.
In combination with the above requirements, the watermark scheme used must have a low degree of obtrusiveness. Thus the quality of the original media must be preserved with little or no perceptual differences between the original media and the watermarked media.
For the context of this paper (and as applied to a cultureware digital repository) we assume that the digital media content can consist of any one (or any combination) of the following:
Each of the above-mentioned media types requires different real-world approaches to embed the watermark. However, the basic approach to watermarking remains the same: the embedding of a redundant message via many low-amplitude, pseudo-noise modifications of the original. The following figure presents a very abstract watermark-embedding process.
The extraction of the embedded watermark is depicted in the next figure. Upon successful extraction of the watermark, ownership information (and other information initially embedded in the original image) is available for inspection.
The following two sequences of images demonstrate a typical watermark embedding and extraction process applied to a static image. It is notable that a slight degradation of the original image occurs when the watermark is embedded. However, the retrieved watermark is very close to the original watermark, which can help resolve ownership issues.
The watermark-embedding process:
| Original Image | Watermark | Watermarked Image |
|---|---|---|
 |
 |
 |
Consequently the extraction process:
| Watermarked Image | Original Image | Extracted Watermark |
|---|---|---|
|
|
 |
The algorithm used in this example is based on work performed by Dr. Coetzee. It makes use of fourth order Daubechies Wavelet Filters combined with watermark redundancy and voting principles to embed and extract the watermark image.
As stated in the previous section, different types of digital media exist, each with their own limitations to embedding a watermark. In this section we will briefly investigate the suitability of each of these media types for digital watermarking.
Digital images are very susceptible to copyright infringements. For this reason the watermarking of digital images has received widespread attention in the literature. Digital media has also proven to be one of the most successful media for digital watermarking as the watermark message can be hidden in the perceptually unimportant areas of an image (i.e., the low-frequency components of an image). The example presented in the previous section clearly indicates the success of digital image watermarking.
Video watermarking can be considered as a superset of normal image watermarking. As such, all the techniques applicable to static images can be applied to video images. However, due to the high frame rate of video, the embedding process must occur almost in real time for live transmissions (it takes a finite time to embed the watermark, which might influence the transmission rate). If the content is generated off-line, this limitation does not exist. A very popular form of on-line (live) video watermarking is the usage of a visible watermark (normally a logo or other distinguishing sign placed in an unobtrusive place on each frame of video footage).
Audio watermarking is currently at the forefront of technology development in an attempt to prevent illegal reproduction and redistribution. One implementation receiving widespread attention is the MP3 approach to audio compression and watermarking.
Audio watermarking can be successfully implemented at frequencies outside the normal human audible range. (This is also the approach followed by compression schemes, in which frequencies outside the human audible range are removed from the original audio soundtrack.)
Text can be subdivided into two categories: raw unformatted ASCII text and formatted text (typically Postscript, PDF or RTF formats).
Watermark information can be embedded into a formatted document using an approach based on the slight adjustment of inter-line and inter-word spacings. Another approach to watermark embedding is to consider the typeset text as one large image and thus to use the typical approaches used for images.
Raw text presents a big problem to the watermark process. At this stage no successful approach is known. One possible approach is based on adding white space characters after each sentence (and is thus hidden to the casual observer). However, this approach is easily bypassed using a normal text editor.
Structured schemes such as 2D and 3D graphic models (e.g., virtual reality or VRML [Virtual Reality Modeling Language]) also require copyright and intellectual property rights protection. Currently, there is no known approach to implement a watermarking scheme for these models. Typically the coordinates are saved in a structured format in the document, with the result that any information added to the model will be easily seen once the model has been rendered. One advantage of many structured schemes is the fact that the models are stored in a proprietary manner, requiring a specific tool to read and render the model. However, this does not prevent the unauthorized distribution of the structured data.
In this section we briefly described the areas where watermarking can successfully be applied. We also highlighted those areas where current watermarking technology fails (raw text and structured schemes).
In our next section we discuss the issue of whether digital watermarking can actually prove ownership
A much-debated issue is whether the presence of a digital watermark can prove ownership. With current technology an attacker might add its own watermark to the media, which can be extracted when confronted. As such the presence of a digital watermark does not prove the ownership. One approach to overcome this problem is to use a governing body (very similar to the approach used with Certification Authorities in the field of digital identities) where all media to be watermarked is registered before general distribution. Combined with the registration the governing body provides a digital certificate proving the rightful owner of the media. Using this approach a possible dispute regarding ownership can be resolved.
In this paper we introduced the concept of digital watermarking used to protect intellectual property rights, copyrights and rightful ownership. We presented required criteria for a watermarking scheme to be successful. We also identified areas (types of digital media) where watermarking can be applied as well as other areas (such as raw text) where no current watermarking scheme exists. We finally addressed the issue of whether the presence of a watermark can prove ownership and concluded that this is only possible through the use of a higher, controlling governing body where all original media can be registered.
A final conclusion: Digital watermarking can successfully be employed if the value of the digital media warrants the added expense. If not, it is an exercise in futility.