Digital Watermarking Full Seminar Report Download

[seminar class]

Presented by:
Abhipsa Dash

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What is watermark
A watermark is a recognizable image or pattern in paper/background that appears as various shades of lightness/darkness when viewed by transmitted light (or when viewed by reflected light, atop a dark background), caused by thickness or density variations in the paper/background.
What is digital watermarking?
The process of digitally inserting a watermark into a multimedia object in such a way that the watermark can be detected or extracted later easily to make an impression about the object and it’s owner is called digital watermarking.
Encoding of watermarking to an object
Let’s denote an image by I, a signature by S and the watermarked image by I’ . E is an encoder function, taking the image I and signature S, and generating a new image called watermarked image (I’).
Mathematically, E(I,S)=I’
Following figure illustrates the encoding process.
Decoding of watermark
A function D takes an image ‘J’ whose ownership is to be determined and recovers a signature S’ from the image. In this process an additional image ‘I’ can also be included which is often the original and un-watermarked version of ‘J’ .
Mathematically, D(J , I )= S’
The extracted signature S’ will then be compared with the owner signature sequence by a comparator function C and a binary output decision generated. It is 1 if there is match and 0 otherwise .
Types of watermarking
1. Image watermarking
a ) Visible watermarking
b ) Invisible watermarking
2.Video watermarking
3. Audio watermarking
4. Text watermarking
Image watermarking
According to human perception image watermarking is of two types
1. Visible watermarking
2. 2. Invisible watermarking
1. VISIBLE WATERMARK:
A visible watermark is a semi-transparent text or image overlaid on the original image. This watermark appears visible to a casual viewer on a careful inspection. Visible watermarks are more robust against image transformation.
2. Invisible Watermarking:
An “invisible watermark” is an embedded image which cannot be perceived with human eye. Only electronic devices can extract the hidden information to identify the copyright owner. It is used to mark a specialized digital content (text, images or even audio) to prove its authenticity.
2. VIDEO WATERMARKING:
The process of watermarking the sequence of video frames is called video
watermarking. To watermark a video file we have to watermark each
frame of the video file.
3. AUDIO WATERMARKING:
The process of embedding information into audio can be termed as audio
watermarking. In case of audio watermarking the time and frequency
property of human ear is used to hide the watermark and make it
inaudible.
4. TEXT WATERMARKING:
The process of embedding/hiding data in text can be termed
as text watermarking. At the time of printout some of the information is
hidden.
Types of possible attacks
THERE ARE MAINLY FOUR TYPES OF POSSIBLE ATTACKS:
• Active Attacks – Hacker tries to remove the watermark or make it undetectable.
• Passive Attacks – Hacker tries to determine whether there is a watermark and identify it. However, no damage or removal is done.
• Forgery Attacks – Hacker tries to embed a valid watermark of their own rather than remove one.
• Decorative Attacks – Hacker applies some distorted transformation uniformly over the object in order to degrade the watermark so that it becomes undetectable/unreadable.