Digital watermarking encodes hidden copyright information into digital content like images, audio, and video. There are three main types of watermarks: visible watermarks that can be seen overlaying the content, invisible watermarks that cannot be seen but can be detected, and robust watermarks that cannot be removed without degrading the content. Watermarking works by adding a watermark signal to the original content signal in either the spatial or frequency domain. It has applications in copyright protection, fingerprinting, authentication, and usage control of digital media.

2. Key Points

3. What is
Digital
Watermarking

4. Encoding
.
Spectral
Framing Analysis
Original
Signal
Watermarked
Signal Watermark DC Carrier
Addition Removal

5. Decoding
Watermarked
Signal Spectral
Framing Analysis
Watermark
Original Signal Processing

6. Classification
Types of Watermarks
Visible Invisible Robust
• Visible Invisible
o A visible translucent An overlaid image which
image which is overlaid cannot be seen, but which
on the primary image can be detected
algorithmically

7. Classification
Visible Watermark
• Any text or logo to verify or hide content
Fw=(1-α)F+ α*W [12]

8. Classification
Invisible Watermark
• Hidden in the signal or content. Cannot be perceived by
human eye or ear. Usually used for authentication or security

9. Classification
Robust Watermark
• Robust: Cannot be manipulated without
disturbing the host signal.

10. Techniques and Schemes
• Spatial domain: In this technique randomly selected
subsets are modified. It is not reliable when
subjected to filtering or lossy compressions
A B
-LSB coding
-Correlation based
Correlation based:- b[i]
a[i]
-Predictive coding I (x,y)=I(x,y)+ K * W(x,y)
w
-Patchwork Iw(x,y) = Watermarked image
I(x,y)=Original image
∑a[i]-b[i]=2N for watermarked image
0 ,other wise
k=gain factor
where N≥1

11. Techniques and Schemes
• Frequency domain: Values of lower frequency
coefficients are altered. This technique is
applied to the whole image.
- Discrete cosine transform (DCT)
- Discrete wavelet transform (DWT)

12. Applications?
Ownership assertion
Fingerprinting
Authentication and integrity
Content labeling
Usage control
Content protection

13. Attacks
• Basic
• Presentation
• Interpretation
• Implementation
• Removal
• Geometrical
• Wavelet Based
- Active
- Passive
- Collusion

14. THANK YOU
QUESTIONS & SUGGESTIONS