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AssigneeKoninklijke Philips Electronics N.V.
InventorsGeert Florimond Gerard Depovere, Antonius Adrianus Cornelis Maria Kalker, Jan Eveleens
Estimating the term…
In a method and arrangement for embedding and detecting a watermark in an information signal, the embedded watermark (Wi) is selected (13) from a plurality of watermarks (W1 . . . WN) in dependence upon a property P of the signal. An example of such a property is the distribution of luminance values of the current video image as calculated by an analysis circuit (12). The corresponding watermark detector performs the same operation: the watermark being looked for depends on the same signal property. It is achieved with the invention that the embedded watermark changes from time to time as a function of the information signal content, so that it cannot easily be hacked.
A method of embedding a watermark in an information signal, comprising the steps:
A method of detecting a watermark in an information signal, comprising the steps:
A watermark embedder for embedding a watermark in an information signal, comprising:
A watermark detector for detecting a watermark in an information signal, comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Robust watermarking, e.g. average attack or collusion attack resistant: using multiple or alternating watermarks
Image watermarking: adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
Television signal processing therefor: for scrambling ; for copy protection
By adding a copy protection signal to the video signal: the copy protection signal being a watermark
Term ended 24 Aug 2023 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The invention relates to a method and arrangement for watermarking an information signal, for example, an audio or video signal. The invention also relates to a method and arrangement for detecting a watermark in such an information signal.
2. Description of the Related Art
FIG. 1 shows, schematically, a block diagram of a watermark embedder in accordance with the invention;
FIG. 2 shows, schematically, a block diagram of a watermark detector in accordance with the invention;
FIG. 3 shows an arrangement illustrating the operation of the watermark embedder and detector;
FIG. 1 shows, schematically, a block diagram of an embodiment of a watermark embedder 1 in accordance with the invention. It will here be assumed that the embedded watermark represents a 1-bit payload. For example, the absence of a watermark indicates that the video signal may freely be copied, whereas the presence of a predetermined watermark denotes that making a copy of the signal is prohibited.
The embedder 1 receives an input video signal I in the form of a sequence of images, and comprises an adder 11 which adds a watermark pattern Wi to each image. The embedder 1 further comprises an image analyzer 12, a selector 13 and a read-only memory 14 in which a plurality of different watermark patterns W1 . . . WN are stored. The analyzer 12 receives the video signal and analyzes a given property P of the video signal as a function of time. The actual value of property P found by analyzer 12 is applied to the selector 13. In response thereto, the selector 13 selects and applies one of the stored watermark patterns W1 . . . WN to the adder 11 for embedding.
The analyzer 12 may take numerous forms. A few examples will be given to provide sufficient teaching to enable a skilled person to design appropriate alternative embodiments. The property being analyzed may be the distribution of luminance values across the image (spatial distribution) or across a sequence of images (temporal distribution). In a first example, the analyzer divides each image into sub-images, and determines which of said sub-images has the highest average luminance. The relevant sub-image number is the actual value of property P. In a second example, the analyzer assigns a “0” to each sub-image having a low average luminance and a “1” to each sub-image having a high average luminance. Each video image is now characterized by an n-bit code, where n is the number of sub-images. The relevant n-bit code is the actual value of property P. The property being analyzed may also be local image activity. Such an analysis can easily be carried out in the frequency domain.