T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 1 A study on the robustness of typical watermarks Johnson Lee Prepared for EECE 575 – Digital Image Processing

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 2 Outline Background Info Techniques –Spatial Domain –DCT Domain –Wavelet Domain Conclusion

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 3 Background – Terminology Watermarking techniques that allow secret communication, usually by embedding or hiding the secret information Fingerprinting special application of watermarking related to copyright protection Copy Protection vs Copyright Protection copy protection inhibits the copy process itself while copyright protection embeds copyright information into an object

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 4 Principles of Watermarking Capacity –As much information as possible Security –Only be accessible by authorized parties Robustness –Resist against attacks Imperceptibility –Invisible

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 5 Principles of Watermarking Capacity –As much information as possible Security –Only be accessible by authorized parties Robustness  Focus of this study –Resist against attacks Imperceptibility –Invisible

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 6 Principles of Watermarking Capacity –As much information as possible Security –Only be accessible by authorized parties Robustness  Focus of this study –Resist against attacks Imperceptibility  Lightly present –Invisible

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 7 Type of Attacks Unintentional –Image compression Ideal watermarking and compression systems inherently mutually exclusive Malicious –Disabling watermark Geometric distortion or noise

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 8 Basic Concept of Watermarking Let O = original image W = watermark M = watermarked image f(x) = some transformation Then, M = O + f(W)

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 9 CDMA Spatial Domain Spread Limited capacity Ideal for small watermarks PSNR =

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 10 CDMA Spatial Resistance JPEG resistant until quality factor 50 No resistance against resizing, rotation Mildly tolerable of mean and median filters – up to [3 3] [3 3][2 2] Common to Many Techniques

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 11 Bruyndonckx (Spatial Domain) Signature generated with input text Based on zone/category classification to embed information  Algorithm use different edge gradients to embed info

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 12 Bruyndonckx (Spatial Domain) Pixel classification, Zone based PSNR = 26407` Original

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 13 Bruyndonckx (Spatial Domain) JPEG resistant until quality factor 50 No resistance against resizing, rotation Mildly tolerable of median and mean filters bit matches: 491/584 correlation: bit matches: 515/584 correlation: bit matches: 421/584 correlation: bit matches: 439/584 correlation: MeanMedian [3 3] [4 4] 5060 bit matches: 394/584bit matches: 538/584 correlation: correlation: SAME PROBLEM AS CDMA SPATIAL DOMAIN

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 14 Comparison-based Correlation DCT Midband

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 15 Comparison-based Correlation DCT Midband - Resistance JPEG resistant until quality factor 28 Geometric – cannot be done because algorithm needs exact size Mean and Median – [4 4] tolerant COMPARISON CDMA & Bruyndonckx JPG – 50 Geo – 0 Median – [3 3] Mean – [3 3] MeanMedian [4 4]

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 16 Cox (DCT Domain) PSNR = Original

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 17 Cox Resistance (DCT Domain) Extremely robust to JPG, Q – 20 Geometric –cannot be done because algorithm needs exact same size as original Mean and Median –Highly resistance since not dependent on high freq noise Correlation [10 10] [6 6] MeanMedian

T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A November 2005Analysis of Attacks on Common Watermarking Techniques 18 Future/In Progress Work Resizing needs to be redone –Most algorithms require input file to be same size as original, can be done by resizing DWT Domain CDMA and advanced DWT techniques