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WatermarkWhat is Watermarking? “Watermarking can be considered as a special technique of Steganography where one message is embedded in another and the two messages are related to each other in some way. “Example :- The presence of specific patterns in currency notes which are visible only when the note is held to light is a well known example for watermark.
Example of a conventional watermark Courtesy of Blue Spike, Inc.
Digital Watermarking is originated from Steganography
Digital WatermarkWhat is Digital Watermarking? “Digital watermarking is similar to watermarking physical objects, except that the watermarking technique is used for digital content instead of physical objects. “
Digital Watermark In digital watermarking a low-energy signal is imperceptibly embedded in another signal. The low-energy signal is called watermark. The main signal in which the watermark is embedded is referred to as cover signal since it covers the watermark. An entity called watermark key used for embedding and detecting watermark signal Watermark key is private
Behind The TechnologySending Side … Watermark Embedding process Water mark Original Image Key Water marked image
Behind The TechnologyReceiving Side … Watermark retrieval process Water marked image Key Confidential message
Types of Digital Watermarking Robust & Fragile Watermarking Visible & Invisible Watermarking Public & Private Watermarking Asymmetric & Symmetric Watermarking Steganograhic & Non-Steganographic watermarking
Robust & Fragile Watermarking Robust Watermarking:-Modification of watermarked content will not affect watermark Fragile Watermarking:-Watermark get destroyed when watermarked content is modified or tampered with
Visible & Invisible Watermarking On Visible watermarking, contents are visible
Visible & Invisible Watermarking (Contn..) Invisible watermarking are not viewed on just looking
Public & Private Watermarking• Public Watermarking Users of content are authorized to detect watermark• Private Watermarking Users not authorized to detect watermark
Asymmetric & Symmetric watermarking In Asymmetric watermarking different keys used for embedding and detecting watermark
Asymmetric & Symmetric watermarking (Contn..) In symmetric watermarking same keys are used for embedding and detecting watermarks
Steganographic & Non- Steganographic Watermarking Steganographic Watermarking User unaware of the presence of a watermark eg:-Used in finger printing applications Non-Steganographic WM:- User aware of the presence of a watermark. e.g.:-User to detect piracy
Digital Watermarking Techniques LSB Watermarking Color Separation Technique Bit Stream Watermarking Word Space Coding, Line Space Coding &Character Coding
Applications of Digital Watermarking. Copy Protection Content Authentication Copyright Protection Metadata Tagging