High performance gray-level watermarking system
AssigneeNational Kaohsiung First University of Science and Technology
InventorsShih-Chang Hsia, I-Chang Jou
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Abstract
The present invention relates to a gray-level watermarking system, in which sub-band and codebook technique are applied, and the feature of progressive transformation is utilized so as to randomly and evenly distribute the watermark to the entire data with the robustness and the visibility reduced. A four-fold key system is developed with encrypted key to exact the watermark, thus forming a system capable of protecting internet-transmitted multimedia signals such as audio, video ones that are combined with the watermark from being detected or attacked.
Claims10
A watermark embedding process using a sub-band filtering, wherein original data are split into N×N blocks and then is transformed into frequency domain with N being not necessarily 8, and a HH band with N/2×N/2 coefficients is tested on a high frequency feature;
- the high frequency being recorded for watermark insertion;
- watermark data being transformed into frequency domain with full picture;
- LL-band coefficients being quantized and inserted into the HH band of a marked block of the original data;
- a composite data of the original data and the watermark data being capable of being created by an inverse transformation of each block of the original data.
Dependencies are inferred from the claim text.