Watermarking in-imageprocessing

Digital Water Marking

By

Sheikh Qaisar Ayub

Advanced Topics in Image Processing

sheikhqaisar@gmail.com

Qaisar Ayub & Sulma Rashid

Watermark

Observe image It is intellectual property

Some one may spend a lot of time And thinking to compose this image

The image has been extended by any other person now he is owner of image

How to protect image ?Problem

Solution Watermark

What ?The term watermark is derived from the German term “Wessmark”

Basic Idea

The basic idea of watermark is to embed some information in digital

images so that it can not be miss used or owned by others

Watermarked imageImage without watermark

Watermark

Visible watermark- The visible watermark consist of visible message of company logo

indicating the ownership of image.

Watermark

Visible watermarkThe implementation of visible watermarks can be applied in following areas

1. Word Document

Types of Digital Watermark

Visible watermarkThe implementation of visible watermarks can be applied in following areas

2. On Images

Types of Digital Watermark

Visible watermark2. Multimedia Files

Types of Digital Watermark

Click on image to Play

Invisible watermark- The watermark will not appear on the image and its existence can be determined

using appropriate watermark extraction or detection algorithm.

ExplanationAn invisible watermark technique consist of an encoding process and a decoding process.

Types of Digital Watermark

Invisible watermark

Types of Digital Watermark

How to implement ?

Step -1Select randomly the area of image to obtain its pixel values

A=

Invisible watermark

Types of Digital Watermark

How to implement ?

Step -2Convert into its binary values

B=

A=

Invisible watermark

Types of Digital Watermark

How to implement ?

Step -3Form a watermarking key

Watermark Key

A=

C=

B=

Invisible watermark

Types of Digital Watermark

How to implement ?

Step -4The OR Operation is used

B=

D= B + C

0110010100000011

01101000

0110010000000001

01100101

0110011000000010

01101000

0110011100000000

01100111

Summery

1. Select randomly area of image and get its pixel values

2. Obtain its digital values

3. Convert to binary

4. Get a key matrix consisting binary values

5. Embed watermark using D:= B OR C

Types of Digital Watermark

A=

B=

C=

Types of Digital Watermark

01100101

00000011

01101000

Encoder Key

Data

ENCODING Algorithm

NoteWatermark will not effect the composition of image

We have add a invisible water mark in the image

The process of embedding the invisible watermark in image is called ENCODING

Achievement

Invisible watermarkWe have embed the watermark in image

Can this image be owned by others?

Types of Digital Watermark

The Answer is yes

What is the function of watermark ?

Example 1. Mr. Ali Compose a image

2. He then embed a watermark in it

3. Later on Mr.Jamil access this image and modify it and clam its ownership

4. Mr.Ali can detect his image by extracting the embedded watermark and can reclaim the ownership

Invisible watermark Decoding- The process of extracting the embedded watermark from image is called Decoding.

- The image can only be decoded by using the decoded algrothem with the key which was used for encoding.

Types of Digital Watermark

01101000

Extract the encoded data from image

Input to Decoding Algorithm

Detect watermark Algorithm

01100101

Example

Extract Watermark Algorithm

Watermark detected by the Algorithm and hence intellectual property can be saved.

Encoding & Decoding

01100101

00000011

01101000

Encoder Key

Data

ENCODING Algorithm

Extract Watermark Algorithm

DECODING Algorithm

Communication Media

01101000

Mathematically Encoding

X’ = EK (X,W)HenceX = Original ImageW= watermark information being embeddedK= user insertion keyE= watermark insertion functionX’ = Watermarked Image

Mathematically Decoding

W = DK’ (X’)HenceX’ = Watermarked imageK’= extraction keyD= watermark extraction functionW= Extracted watermarked information

We have understand the process of extracting the watermarked key from image

Encoding and Decoding Mathematically

Achievement

Application of watermark

1. Ownership Declaration

Application of watermarkFinger Print IS File save ?

Application of watermarkFinger Print

Data Center-01

Data Center-02

Data Center-03

Network

Application of watermarkFinger Print

A invalid copy is found at any location

Extract the embedded figure print From file

A figure print is unique value form each data center

Can identify the data center

Application of watermark

Embed the number of copies to be allowed for copying embed in the hardware

4

4 3 2 1

Copy not allowed

Click on image to Play

Application of watermarkFraud Detection

Data Center-01

Data Center-02

Data Center-03

Network

5. ID Card & Security

Application of watermark

Muhammad IshfaqueKarim Ahmad

Observe ID card

WHAT IS THE PROBLEM ?

5. ID Card & Security

Application of watermark

Muhammad Ishfaque

Muhammad Ishfaque

Extract name using watermarked algorithm

Muhammad Ishfaque

Compare the to validate ID CARD.

M Jamil

M.jamil

M.jamil

Muhammad Ishfaque

We have understand the application of water mark

Achievement

Robustness

The ability of watermark to provide the resistance against the modification of image is

called robustness

Modification

Original Image

Properties of Watermark

Resize Rotation & Compression

No perceptibility

“ When we embed a invisible watermark by changing it bits it will not effect Human visual

system”

Modification

Original Image

Properties of Watermark

Watermarked image

Non Detectable

Design a watermark that is not detectable by the outer attacks

Complexicity

The amount of time required to encode & decode a image is called complexicity

Properties of Watermark

We have understand the properties of watermarks

Achievement

Methods of Water MarkingWater Marking in Spatial domain

The values of the image pixels are directly modified based on the

water mark that has to be embedded.

Advantage

- Simple

- Less computational required

Drawback

- No security against modification

Water marking in frequency domainA distributed sequence inserted into the perceptually most significant

frequency components.

Image: 11001010 00110101 00011010 00000000...

Watermark: 01 01 10 11...

Watermarked Image:11001011 00110010 00011100 00000011...

Methods of Water Marking

Thanks