MASTER THESIS Video Watermarking - Computer Graphics Group ...

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5.4.7 Sharpening Sharpening is a kind of high-pass filter mentioned in Section 4.3.1, thus high probabilities are expected in case of noise method. The test uses MPlayer “unsharp” filter with opposite coefficient than in the blurring test. Again, three convolution sharpening masks are applied (see column in Table 10 named SM). Table 10: Sharpening test results The sharpening filter works pretty well not only when using noise method but also when using both block and coefficient methods. The test results show that it does not matter which size of the convolution mask is used. 46
5.4.8 Multiple Watermark Embedding Multiple watermark embedding test measures influence of watermarking already watermarked video sequences. Five watermarks generated from five different copy IDs have been subsequently embedded. Sequence numbers of the copy IDs used in the detection process are listed in Table 11 in column named C#. In case of block method, the test proves overwriting of previously embedded watermarks, as supposed in Section 4.3.2. Coefficient method chooses one of 8 coefficients for watermark element embedding. Therefore, the overwriting is expected when embedding more than 8 watermarks. This hypothesis has been proved by an additional test with 20 watermarks. No impairment is expected in case of noise method because different noise patterns are statistically independent. Table 11: Multiple watermark embedding test results 47
Page 1 and 2: Charles University in Prague Facult
Page 3 and 4: Table of Contents Abstract 5 1 Intr
Page 5 and 6: Název práce: Watermarking videa A
Page 7 and 8: information about copyright owner a
Page 9 and 10: Common geometric distortions - the
Page 11 and 12: watermark, i.e. values of the water
Page 13 and 14: Chapter 3 The H.264 Standard The H.
Page 15 and 16: There are three types of slices: I,
Page 17 and 18: frequency transform. The choice is
Page 19 and 20: Chapter 4 Implementation Details Th
Page 21 and 22: auxiliary coded pictures), Supplem
Page 23 and 24: an intra coded slice, content ID -
Page 25 and 26: samples is subtracted from the resi
Page 27 and 28: At the beginning of the entire proc
Page 29 and 30: file in order to provide detailed r
Page 31 and 32: as a part of the whole process. The
Page 33 and 34: coefficients are hardly set to non-
Page 35 and 36: Table 1 outlines characteristics of
Page 37 and 38: The third and the fourth row sets c
Page 39 and 40: Using block method, we cannot consi
Page 41 and 42: probabilities of watermark detectio
Page 43 and 44: 5.4.3 Cropping In the cropping test
Page 45: 5.4.6 Blurring Blurring can be cons
Page 49 and 50: Despite the expectations, all the m
Page 51 and 52: ecompression and noising, and to so
Page 53 and 54: Bibliography [1] Ingemar J. Cox, Jo
Page 55 and 56: Appendix A Enclosed CD & Installati
Page 57 and 58: Appendix B The plugin usage The wat
Page 59: length is the length of the list of

MASTER THESIS Video Watermarking - Computer Graphics Group ...

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