Digital watermarking system and drift compensating system
AssigneeKddi Corporation
InventorsShigeyuki Sakazawa, Yasuhiro Takishima
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Abstract
An object of the present invention is to perform DCT coefficient operation and drift compensation for embedding watermark data with the small amount of computing. An MB data extraction unit extracts a macro block or block into which the watermark data is embedded on the basis of a template. Additionally, a DCT coefficient extraction unit extracts the DCT coefficient at a position into which the watermark data is embedded according to a direction of the template. A DCT coefficient operation unit performs the process of embedding the watermark data or the process of compensating the drift to the extracted DCT coefficient.
Claims6
A system for compensating drift of a digital watermark, comprising:
- means for performing an operation for canceling the effect of a DCT coefficient alteration performed in an nth MPEG-encoded frame, n is a positive integer, to DCT coefficients of frames subsequent to the nth frame at a same position as a position where the digital watermark is embedded in the nth frame by referring to the alteration operation of the nth frame,
- wherein the digital watermark is embedded by a digital watermarking system comprising means for selecting a block from MPEG-encoded data;
- means for selecting a DCT coefficient from the selected block;
- and
- means for performing alteration so that a quantization level value of the selected DCT coefficient is increased by a value not lower than one.
A system, comprising:
- a digital watermarking system comprising
- means for selecting a block from an nth, n is a positive integer, frame of MPEG-encoded data;
- means for selecting a DCT coefficient from the selected block;
- and
- means for embedding a digital watermark in the selected block by increasing a quantization level value of the selected DCT coefficient by a value not lower than one;
- and
- means for compensating drift to a DCT coefficient in a frame subsequent to the nth frame by referring to an operation of the nth frame, the DCT coefficient in the subsequent frame being located at a same position as a position at which the digital watermark is embedded in the nth frame,
- wherein the means for compensating drift to the DCT coefficient in the frame subsequent to the nth frame performs an operation for canceling the effect of the drift performed on the DT coefficient in the nth frame when embedding the digital watermark.
Dependencies are inferred from the claim text.