prepared for da 201 introduction to digital watermarking
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Prepared for DA 201
Introduction to Digital Watermarking
What is a watermark?
Originally developed…end of 13th century
Used to differentiate paper makers of the time
Oftentimes a company logo overlaid on digital images used by photographers
Types of watermarking
Video watermarking
Image watermarking
Audio watermarking
How does it work?
Watermark can be digitally embedded in images
Done for copyright protection purposes
Central database of image digests is kept
Periodic searches of the www are done…for images having the same digest
Digital watermarking: provides a way to protect the rights of the owner of a file, the owner can prove it is his.
You can still see the image or document… can preview the image, but not use it until you purchase the rights to it.
Properties of digital Watermarking
-hides data in a file
-the act of hiding data makes it a form of steganography for protecting and proving ownership…not for transmitting info
- if watermark is removed…..image will be destroyed.
Digital Watermarking
When you apply a watermark to a file
You are modifying the file This is referred to as noise
Can it be seen?
Digital watermarking is imperceptible to human senses
Easily recognized by software or hardware detectors
DW remains constant through compression & decompression
Is it robust?
Digital Watermark remains constant through
encryption & decryption very effective for distributing
digital & analog media
Who uses Digital Watermarking? Photographers… to identify & manage
image copyrights
Movie studios…. to deter piracy of movies, music & DVDs
Record labels… to deter piracy
TV broadcasters…to track, verify & measure TV and radio programming & advertising
Corporations… to authenticate IDs and deter identity theft and fraud & document counterfeiting
Who uses digital watermarks? Satellite image providers……to identify
ownership & enhance the value of geospatial intelligence information
Enables media serialization of digital content….making identification of specific instances of content possible!!!
Sometimes watermark is embedded in audio signal…Serial Code Management (digital copy prohibited)
Why do they use it?
To identify Protect Manage the rights to content (IP)
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