Digital Water Mark 2-9

Digital Watermarking in Digital Watermarking in Image Processing Image Processing

Presented by Presented by

Miss. Archana B. Miss. Archana B. DholeDholeM.Tech. IIIrd Sem.M.Tech. IIIrd Sem.(CSE) R.C.E.R.T. (CSE) R.C.E.R.T. ChandrapurChandrapur

Contents.Contents.

Introduction to Digital Watermarking Introduction to Digital Watermarking in Image Processing.in Image Processing.

What is digital watermarkingWhat is digital watermarking Types of Digital WatermarkingTypes of Digital Watermarking ClassificationClassification Phases of Digital Watermarking.Phases of Digital Watermarking. ApplicationsApplications

Introduction

A digital watermarking provides authentication and copyright protection for multimedia contents over the internet.

A digital watermarking is a technique for inserting information into an image or text or audio which can be later extracted for various purposes including identification and authentication.

A digital watermark is a piece of information that is hidden in a multimedia content, in such a way that it is imperceptible to a human observer, but easily detected by a computer.

Introduction(Contd.) The principal advantage is that the

watermark is inseparable from the content . Digital watermarking is the process of

hiding the watermark imperceptibly in the content.

This technique was initially used in paper and currency as a measure of authenticity.

The primary tool available for data protection is encryption. Encryption protects content during the transmission of the data from the sender to receiver.

What is watermarking & Digital watermarking

Watermarking can be considered as a special technique of steganography where one message is embedded in another and the two messages are releated to each other in same way.

Digital watermarking is similar to watermarking physical objects except that the water marking technique is used for digital content instead of physical objects.

Types

Based on visibility of watermarks

- Visible Watermarks

- Invisible Watermarks

Based on the content to be watermarked

- Text Watermarking

- Image, Audio, Video Watermarking

Classification

Based on processing method used watermarking can be classified as

Spatial domain technique. Transform domain technique. Spatial Watermarking: Just change some of the

values of the pixels in the lower bit plane; e.g., Change some of the bits from 1 to 0 or 0 to 1.

Frequency Domain Watermarking: First convert the image to the frequency domain and then apply the watermark in the low frequency regions.

Phases of Digital Watermarking

Digital Watermarking involves two major phases: (i) Watermark embedding, and (ii) Watermark extraction.

Digital watermarking life-cycle phases

General digital watermark life-cycle phases with embedding-, attacking-, and detection and retrieval functions

The information to be embedded in a signal is called a digital watermark, although in some contexts the phrase digital watermark means the difference between the watermarked signal and the cover signal.

The signal where the watermark is to be embedded is called thehost signal.

A watermarking system is usually divided into three distinct steps, embedding, attack, and detection.

Phases of Digital Watermarking(contd.)

Phases of Digital Watermarking(contd.)

In embedding, an algorithm accepts the host and the data to be embedded, and produces a watermarked signal.

Then the watermarked digital signal is transmitted or stored, usually transmitted to another person. If this person makes a modification, this is called an attack.

Phases of Digital Watermarking(contd.)

Detection (often called extraction) is an algorithm which is applied to the attacked signal to attempt to extract the watermark from it.

If the signal was unmodified during transmission, then the watermark still is present and it may be extracted.

Original Image without watermark

Image with watermark

Algorithms

Frequency-domain techniques The frequency-domain techniques mainly

used for watermarking of the human visual system are better captured by the spectral coefficients.

The transforms are broadly categorized in two ways

(a) Discrete Cosine Transformation (DCT) (b) Discrete Wavelet Transformation

(DWT)

Algorithms(Contd.)

The following figures are explained about Discrete Cosine Transformation and Discrete Wavelet Transformation.

Watermark embedding steps.

Watermark extracting steps.

Applications Digital watermarking may be used for a wide

range of applications, such as: Copyright protection Source tracking (different recipients get

differently watermarked content) Broadcast monitoring (television news often

contains watermarked video from international agencies)

Online music industry.Online music industry. News gathering using digital cameras.News gathering using digital cameras.

Thank You.Thank You.