21 March 2005 Watermarking in JPEG bitstream
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Abstract
In a previous work we proposed an algorithm to embed watermark bits directly in a compressed bitstream. The embedding algorithm is reversible, requires no decompression, causes no increase in file size, and is fast. The problem is that the watermarked bitstream will either lose format-compliance or suffer unacceptable visual degradation. We have now solved these problems for JPEG streams. The algorithm determines the AC VLC codespace that is actually used by the image. Watermarking specific VLCs places the resulting codewords outside of the used codespace, but still within the orignal VLC table specified in JPEG standard. To keep the watermarked stream format-compliant and visually acceptable, the run/size values of watermarked VLCs are remapped in a way to keep visual degradation to a minimum. Since watermarked VLCs are never used in the image, this remapping does not alter the image outside of watermarked VLC codespace.
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Robert J. Berger, Robert J. Berger, Bijan G. Mobasseri, Bijan G. Mobasseri, } "Watermarking in JPEG bitstream", Proc. SPIE 5681, Security, Steganography, and Watermarking of Multimedia Contents VII, (21 March 2005); doi: 10.1117/12.585969; https://doi.org/10.1117/12.585969
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