1. DIGITAL
WATERMARKING

2. Contents
 What is DWM ?
 Applications
 Classification
 Working
 Attacks
 Advantages and Disadvantages
 Techniques

3. Digital Watermarking
 We add ‘Visible’ or ‘Invisible’ structure called ‘Watermarks’
to digital media. The process of adding watermarks is called
‘Digital Watermarking’.
 Adaptation of Paper Watermarks.
 Describes methods and technologies that allow to hide/embed
various types of information to digital document.
 In general Digital Watermarking means “Author Signature”.

4. Applications
 Copyright Protection
 Owner Identification
 Content Authentification
 Proof of Ownership

5. Classification
 Perceptible Watermarks and Imperceptible Watermarks
 Robust Watermarks and Fragile Watermarks
 Private Watermarks and Public Watermarks

6. Classification (contd.)
 Perceptible Watermarks and Imperceptible Watermarks
 Perceptible Watermarks are visible to human eye
 Useful for primary Applications.
E.g. of watermark in a video
E.g.. Of watermark in a image
 Imperceptible watermarks are Invisible to human eye.
 Used in the places where the content being watermarked must
appear in unchanged form.
 Remains hidden in content and can be detected only by authorized
agencies.

7. Classification (contd.)
 Robust Watermarks and Fragile Watermarks
 Degree to which watermarks can withstand any modification of any
type (Accidental or Intentional ).
 Robust Watermarks are difficult to remove from the object in which
they are embedded.
 Perceptible Watermarks are more Robust.
 Fragile Watermarks can be easily destroyed by any attempt to
temper with them.

8. Classification (contd.)
 Private Watermarks and Public Watermarks
 Private Watermark requires at least original data to recover
watermark.
 They are also known as ‘Secure Watermarks’.
 Public Watermark requires neither original data nor embedded
watermark to recover watermark information.

9. Working
 Typical DWM system consists of mainly 3 parts / process
 Watermark Insertion
 Watermark Extraction
 Watermark Detection

10. A Generic Watermarking System
Cover Work
Watermarked Detected
Watermark Watermark
Watermark
Embedder Work Detector
Message
Watermark Message

11. User Key
Watermarked
Input Image Watermark Insertion
Image
Watermark
User Key
Extracted
Watermark Extraction
Watermarked Watermark
Image
User Key
Watermarked Decision
Watermark Detection
Image ( Yes or No )
Specified ID
( Watermark )

12. General Digital Watermarking Process
(a) Watermark Embedding
Digital Watermark
0101 …. . . .. . .
Original Data Watermarked Data
Embedding
Algorithm 0101 …. .
Distribution

13. General Digital Watermarking Process (contd.)
(b) Watermark Extraction
Original
Data
Watermarked Data
Extracted Watermark
Extraction
0101 …. . 0101 …. . . .. . .
Algorithm

14. Attacks
 Mosaic Attack
 Stir mark Attack
 Geometric Attack
 Subtractive
 Distortive
 Forgery Attack

15. Attacks (contd.)
Mosaic Attack

16. Attacks (contd.)
Stirmark

17. Attacks (contd.)
 Geometric Attack
 Subtractive Attack involves ‘removing’ the mark by cropping or
digital editing.
 Distortive Attack attempts to make some ‘uniform distortive
changes’ in the image such that mark becomes ‘unrecognizable’.

18. Attacks (contd.)
 Forgery Attack
 Also known as ‘Additive Attack’.
 The attacker include his/her own watermark overlaying the original
image and marking the content as their own.

19. Advantages
 Uniquely identifies the author of copyrighted work.
 Implementation on PC platform is possible.
 Embedding watermark is easy
 Image Tampering Detection

20. Disadvantages
 Watermarking doesn’t prevent image copying but we can track
down and detect ownership of copied images.
 Watermarks vanishes if someone manipulates the image.
 Resizing, compressing images from one file type to another
may diminish the watermark and it becomes unreadable.

21. DWM Techniques
 Image Domain Encoding
 Also known as Least Significant Bit (LSB).
 LSB works by reducing the no of colors used by image itself and
uses the rest of the palette to encode the information.
 If the colors in an image are less then more information can be
stored without quality loss.

22. Thank you
Question ??