1. Integrity of multimedia data ● Techniques for digital watermarking ● An example in the Wavelet domain ● Experimental results: evaluation

2. Watermarking ● Basic idea To insert a invisibile structure (watermark) inside a «host» signal in order to mark it ● Result Author identification Author identification Which alteration? Which quality? Which alteration? Which quality? Evalutaion of the similarity between the original and teh altered data Evalutaion of the similarity between the original and teh altered data

3. Applications Applicazioni Copyright Protection Authentication Hidden annotation Secret communication E-commerceVideo-on-demandE-commerceforensic Multimedia distributuion medical imaging cartograpgy indexing & retrievial Military and intelligence Alternatives to cryprography

4. Example ● Method Request analysis Request analysis Choice of watermarking techniques Choice of watermarking techniques Improvements on the state-of-the- art Improvements on the state-of-the- art

5. Method ● «musts» Do not compromise the image quality Do not compromise the image quality Capable to reveal unauthorized modification Capable to reveal unauthorized modification JPEG2000 compression is «legal» JPEG2000 compression is «legal» unauthorized modifications are difficult unauthorized modifications are difficult To localize altered area To localize altered area

6. Robust self-embedding watermarking Method ● Tecnica di watermarking Fase di CASTING Fase di DETECTION Confronto

7. Method ● Improvements Watermark is less visible Watermark is less visible Correct thealterations Correct thealterations Resistant to JPEG 2000 compression Resistant to JPEG 2000 compression

8. The algorithm: casting Self Embedding DWT Correction error code Quantization and binarization IDWT DWT Quantization and binarization

9. Self Embedding DWT Codice a correzione d’errore Quantization and binarization Quantization and binarization IDWT The algorithm: casting Quantization function

10. Casting Correction error code Parity Bit 01001…011 Base band Self Embedding DWT Correction error code Quantization and binarization IDWT

11. Casting Binary Code Golay (23,12) … 1 101 1 0 0 v 0 12 … 1 101 1 0 0 0 23 Self Embedding DWT Correction error code Quantization and binarization IDWT

12. IDWT Casting Low Bit Modulation (LBM) Test on JPEG2000 Coefficienti wavelet autenticati Coefficienti wavelet per inserimento watermark Coefficienti wavelet non utilizzati Self Embedding DWT Correction error code Quantization and binarization IDWT

13. Detection W Extraction DWT Quantization and Binary representation Error correction code Golay (23,12) … 1 101 1 0 0 v 0 12 … 1 101 1 0 0 0 23

14. ● Which Metric? ● Evaluation of watermarking percetion ● Evaluation of robustness ● How to reveal and correct alterations? Experimental results ● Which images?

15. Test Images Medical Syntethic Standard Naturalistics 62 images in 4 categories

16. Metrics Similarity between watermark Similarity between images

17. Is it visible? 3 Livelli di decomposizione 5 Livelli di decomposizione Immagine Originale Risultati sperimentali 3 Livelli di decomposizione 5 Livelli di decomposizione

18. Experimental results What about robustness??? Simple attacks Simple attacks Gaussian noise Gaussian noise Median filter Median filter Gaussian filter Gaussian filter lossy compression JPEG2000 lossy compression JPEG2000 removal attacks removal attacks Removal of watermark Removal of watermark removal of an area of the image removal of an area of the image Loss of synchronization Loss of synchronization

19. Robustness to compression JPEG2000 Simple attacks

20. Removal of an area of the images PSNR Difference PSNR Removal attacks

21. Experiments Removal and corrections Immagine originaleImmagine marchiata e compressa Immagine manipolataErrori rilevatiErrori rilevati nel dominio spazialeErrori rilevati nel dominio DWTImmagine ricostruita