354 | IETE TECHNICAL REVIEW, Vol 23, No 6, 2006 |
6. RESULTS where w is the true author watermark, w is the extracted
mark, and Nw is the length of the watermark. The
value of TAF ranges between zero and one. The
presence of tampering is determined if TAF(w,w)≥ An averaging attack on the watermarked image using a 2-D 3×3 filter was simulated. The function of an averaging attack using a 3×3 filter is to place average value of the 8 adjacent pixel at the central pixel if the grid.
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The resultant image is shown in Fig 6.Wavelet based watermark detection scheme was
applied on this filtered image for the detection of
tampering in the images and TAF(w,w) was found to
be higher than the threshold
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