Digital Watermarking and its Types

Digital Watermarking is use of a kind of marker covertly embedded in a digital media such as audio, video or image which enables us to know the source or owner of the copyright. This technique is used for tracing copyright infringement in social media and knowing the genuineness of the notes in the banking system. Types of Watermarks :

1. Visible Watermarks – These watermarks are visible.
2. Invisible Watermarks – These watermarks are embedded in the media and use steganography technique. They are not visible by naked eyes.
3. Public Watermarks – These can be understood and modified by anyone using certain algorithms. These are not secure.
4. Fragile Watermarks – These watermarks are destroyed by data manipulation. There must be a system which can detect all changes in the data if fragile watermarks are to be used.

Digital watermarking process (Life cycle) : The information needs be embedded in the media. The signal which is embedded is the host signal and the information is called digital watermark. The process has 3 main parts:

1. Embed – In this part, the digital signal is embedded with the digital watermark.
2. Attack – The moment when the transmitted media is changed, it becomes a threat and is called an attack to the watermarking system.
3. Protection – The detection of the watermark from the noisy signal which might have altered media (JPEG compression, rotation, cropping, and adding noise) is called Protection.

Applications :

• Watermarks are used in forensics. Tampered evidence is unacceptable in forensics and Watermarked images are acceptable.
• This is used by brands. The Digital Watermarking is done so that the authority of the digital media is intact.
• Digital Watermarking prevents copying of the data.
• Video editing software use watermarks so that people buy the full version of it.
• It is used in video authentication. News channels often show videos of other agencies which are watermarked. It is also used for ID card security.
• It is used for content management in social media.

Advantages :

• It is used in detecting copyright infringements of digital content.
• Watermarking is a very secure technique. The embedding of watermarks is done by a key. Anyone who wants to remove the watermark can only do this with the knowledge of the keys involved in embedding.
• The embedded version of a file is also digital in nature which can be transmitted and used easily. No change in file format ensures that there is no error or difficulty in using watermarked media.

Disadvantages :

• Watermarks that are visible are easily removed or overlayed by other watermarks.
• There still needs to be invention of more robust techniques to watermark pictures. The pictures with watermarks are easily resized and the watermarks can be cropped.
• The owners can remove watermarks easily. This means that if anyone on the owner side can easily manipulate the image and alter the watermark.