26-05-2012, 02:58 PM
DIGITAL WATERMARKING
[attachment=23175]
What is digital watermarking..?
Digital watermarking is the process of embedding “information” into a digital media without compromising the media’s value in a way that it is difficult to remove.
The term ‘watermark’ was introduced near the end of the 18th century. It was probably given because the marks resemble the effects of water on paper.
History in brief…
Was used in ancient Italy for indicating the paper brands and name of mills.
In 18th century to prevent money counterfeting.
The first example of a similar technology was done by Emil Hembrooke in 1954 for identifying music works.
Later it was used by Komatsu and Tominaga in 1988.
Terminologies…
Steganography
Watermarking
Data hiding and data embedding
Copy protection
Copyright protection
Steganography-is an art,science,study, work of communicating in a waywhich hides a secret message in the main information.
Steganography methods rely generally on the assumption that the existence of the covert data is unknown to unauthorized parties and are mainly used in secret point-to-point communication between trusting parties.
Watermarking- as opposed to steganography – in an ideal world can resists attacks. Thus, even if the existence of the hidden information is known, it should be difficult for an attacker to remove the embedded watermark, even if the algorithmic principle is known.
Copy protection- attempts to find ways, which limits the access to copyrighted material and/or inhibit the copy process itself.
Copyright protection- inserts copyright information into the digital object without the loss of quality. Whenever the copyright of a digital object is in question, this information is extracted to identify the rightful owner.
Framewrok
Watermarking is the process that embeds data called ‘watermark’ into a media such that watermark can be detected or extracted later to make an assertion about the media. For example, digital watermarking technique for images is to add a visible seal to the existing image.
Watermarking techniques…
According to the working domain
According to the type of document
According to the human perception
According to the application
Spatial domain
Is applied to graphic images and text.
Slightly modifies the pixels of one or two randomly selected subsets of an image.(generally the lower bits).
However, not reliable when subjected to normal media operations such as filtering or lossy compression.
Frequency domain
also called transform domain.
Values of certain frequencies(normally low) are altered from their original.
The watermark is applied to the whole image so as not to be removed during a cropping operation and also to make its verification difficult.
[attachment=23175]
What is digital watermarking..?
Digital watermarking is the process of embedding “information” into a digital media without compromising the media’s value in a way that it is difficult to remove.
The term ‘watermark’ was introduced near the end of the 18th century. It was probably given because the marks resemble the effects of water on paper.
History in brief…
Was used in ancient Italy for indicating the paper brands and name of mills.
In 18th century to prevent money counterfeting.
The first example of a similar technology was done by Emil Hembrooke in 1954 for identifying music works.
Later it was used by Komatsu and Tominaga in 1988.
Terminologies…
Steganography
Watermarking
Data hiding and data embedding
Copy protection
Copyright protection
Steganography-is an art,science,study, work of communicating in a waywhich hides a secret message in the main information.
Steganography methods rely generally on the assumption that the existence of the covert data is unknown to unauthorized parties and are mainly used in secret point-to-point communication between trusting parties.
Watermarking- as opposed to steganography – in an ideal world can resists attacks. Thus, even if the existence of the hidden information is known, it should be difficult for an attacker to remove the embedded watermark, even if the algorithmic principle is known.
Copy protection- attempts to find ways, which limits the access to copyrighted material and/or inhibit the copy process itself.
Copyright protection- inserts copyright information into the digital object without the loss of quality. Whenever the copyright of a digital object is in question, this information is extracted to identify the rightful owner.
Framewrok
Watermarking is the process that embeds data called ‘watermark’ into a media such that watermark can be detected or extracted later to make an assertion about the media. For example, digital watermarking technique for images is to add a visible seal to the existing image.
Watermarking techniques…
According to the working domain
According to the type of document
According to the human perception
According to the application
Spatial domain
Is applied to graphic images and text.
Slightly modifies the pixels of one or two randomly selected subsets of an image.(generally the lower bits).
However, not reliable when subjected to normal media operations such as filtering or lossy compression.
Frequency domain
also called transform domain.
Values of certain frequencies(normally low) are altered from their original.
The watermark is applied to the whole image so as not to be removed during a cropping operation and also to make its verification difficult.