We continue our series on Issued Patents. Assigned to ContentGuard, the first of today's patents describes a protected content distribution system. Assigned to Electronics and Telecommunications Research Institute (KR), the second patent describes a method for blindly embedding and extracting a watermark by using wavelet transform and an human visual system model.
7,290,699, "Protected content distribution system," assigned to ContentGuard.
A rights management system, method and device for managing use of items having usage rights associated therewith by enforcement of the usage rights with repositories, including a client device adapted to request an item and receive the item and a usage right associated with the item and specifying a permitted manner of use of the item; and a server device adapted to send the item and the associated usage right to the client device in response to the request. The client device includes means for establishing a communication between the client device and a third party entity associated with the rights management system based on a received item and associated usage right.
7,292,708, "Method for blindly embedding and extracting a watermark by using wavelet transform and an HVS model," assigned to Electronics and Telecommunications Research Institute (KR).
The present invention relates to a method for blindly embedding and extracting a watermark by using wavelet transform and a human visual system (HVS) model, which obtains both robustness and invisibility by applying the HVS model of NVF or JND imitating a human visual system to a middle frequency band for wavelet transformation and using a quantization step determined adaptively according to the importance of wavelet coefficient. A method according to the present invention includes the steps of: decomposing an original image by a wavelet and selecting a middle frequency band as a watermark embedment area; obtaining an HVS model having a human visual recognition information at each embedding position; determining the importance of the coefficient for each embedding position, and adaptively determining a quantization step for each embedment location by using the importance and the HVS model; quantizing each pair of embedment area by the quantization step and variably embedding a watermark sequence into a middle frequency band according to a value of the watermark; and performing inverse wavelet transform on an overall area into which the watermark sequence is embedded, and generating a watermarked image.