Digital watermarking

Digital Image WatermarkingDigital Image Watermarking

Presented By:-

Mohd Nafees Ansari

08peb-247

Mohammad Mukeel

08peb-306

Under Supervision of

Mr. Izharuddin

(Reader in Computer engg. Dept)

What is Digital Image Watermarking?

Digital Image Watermarking is a technique for

inserting information (the watermark) into an image, which can be later extracted or detected for variety of purposes including identification and authentication purposes.

Why Need ?

RequirementsRequirements

Hardware Requirements:

-RAM :512MB

-Hard disk :4.0GB

Software Requirements:

-Operating system : Windows7

-Language : Matlab

Cover Image & message image : Grayscale image

Size of cover image is greater than the message image

A digital watermark can be.

Visible Watermark In visible watermarking, the information is visible in the picture or

video. The information is text or a logo which identifies the owner of the media.

Invisible Watermark In invisible watermarking, information is added as digital data to audio,

picture or video, but it cannot be perceived as such (although it may be possible to detect that some amount of information is hidden).

Watermarking Domain

Spatial Domain Wavelet Domain Frequency Domain

Spatial Domain Approach:

The earliest watermarking techniques are mainly this kind and the simplest

example is to embed the watermark into least significant bits(LSB) of the image

pixels.

This technique has relatively low information hiding capacity and can

be easily erased by lossy image compression.

Wavelet Domain

The DWT (Discrete Wavelet Transform) separates an image into a lower resolution approximation image (LL) as well as horizontal (HL), vertical (LH) and diagonal (HH) detail components. The process can then be repeated to computes multiple “scale” wavelet decomposition, as in the 2 scale wavelet transform shown below in figure

FREQUENCY DOMAIN APPROACH

F L

FM

Digital Watermarking ProcessDigital Watermarking Process

FEATURES OF DIGITAL WATERMARKINGFEATURES OF DIGITAL WATERMARKING

o Imperceptibility (slight change)

o Robustness

o Inseparability

o Security

Classifications of digital watermarkingClassifications of digital watermarking

o Robust watermark It sticks to document ( image, audio, video or text) to which it is

embedded. Removing it destroys the quality of signal. It is used for copyright protection.

o Fragile Watermark It breaks very easily on modifying host signal. It is used for

temper detection, finger printing and digital signature.

o Semi Fragile Watermark It is sensitive to signal modification and gives information about

nature and location of attack also, it provides data authentication.

Least Significant Bit

It is based on the substitution of LSB plane of the cover image with the given watermark.

Embedding watermark: Read the cover image. Determine the size of the cover image. Read the message image. Determine the size of the message image. Take pixel value of cover image. Convert into binary. Replaces the LSB of cover image with the binary value of bits of message image .

Recover Watermark:

Thereafter, make a function that extracts your watermark from a watermarked image. The function should take as input a watermarked image and give the extracted watermark as output.

Recover watermark in LSB

Watermark in wavelet domain Watermark insertion Set the gain factor for embedding. Read in the cover object. Determine size of watermarked image. Read in the message image and reshape it into a vector. Add PN-sequences to h1 and v1 components when message = 0, according to the

formula:

Perform IDWT. Convert back to uint8. Write watermarked image to file. Display watermarked image.

Watermark extraction

Read in the watermarked object. Determine size of watermarked image. Read in original watermark. Determine size of original watermark. Initialize message to all ones. Add PN-sequences to h1 and v1 components when message = 0. Reshape the message vector and display recovered watermark. Display recovered message. Calculate the quality of recovered image by using PSNR function

FUTURE DEVELOPMENT

o In this project we use a gray scale image for watermark image to insert into

original image. In future, we use a color images.

o Watermarking in Discrete Wavelet Transform domain.

o Watermarking in Discrete Cosine Transform (DCT) domain.

Applications

Documents and image security Copyright protection Copy Protection Content Authentication Broadcast monitoring Digital Fingerprinting Temper Detection

References

http://en.wikipedia.org/wiki/Digital_watermarking   http://www.mathworks.com/ -- An online help for working in

MATLAB.

An Introduction to Digital Image Processing with Matlab Matlab An introduction with Applications by Amos Gilat.

Thank You