What is Sparse Watermark

Media that is distributed digitally can be copied and redistributed illegally. Embedding an individual watermark in the media object for each customer will make it possible to trace pirate copies to the redistribution source. However, digital distribution methods such as broadcast and multicast are scalable and will give all customers identical copies of the media content. Distribution of individually watermarked media is more difficult to achieve. In this chapter, methods for how media with individual watermarks can be distributed scalable are presented and discussed. These methods are categorized in four groups. One group that is based on watermark embedding in the network, another group for embedding in the client, and two groups that use fragments of the media content that are unique for each customer or shared among a subgroup of customers.