Real Time Implementation of Digital Watermarking Algorithm for Image and Video Application
Amit M. Joshi, Vivekanand Mishra, R. M. · InTech eBooks · 2012
Data hiding techniquesCryptography: It scrambles a message into a code to obscure its meaning.Scrambling of message is done with help of secret key.Scrambling message called as encrypted and it is again decrypted with that secret key only.Cryptography provides security to message.Steganography: With Steganography, the sender would hide the message in a host file.The host file or cover message, is the file that anyone can see.When people use this techique, they often hide the true intent for communicating in a more common place communication scenario.In steganography, usually the message itself is of value and must be protected through clever hiding techniques and the "vessel" for hiding the message is worthless.Watermarking: It is the direct embedding of additional information into the original content or host signal.Ideally, there should be no perceptible difference between the watermarked and original signal and the watermark should be difficult to remove or alter without damaging the host signal.In watermarking, the effective coupling of message to the vessel which is the digital content is of value and the protection of the content is crucial.In case of steganography, where the method of hiding the message may be secret and the message itself is kept secret; but in watermarking, typically the watermark embedding process is known and the message (except for the use of a secret key) does not have to be secret.Most of the people find difficulty to differentiate term digital watermarking and steognography.Let us take a simple example to understand this difference.If someone gives me a beautiful birthday gift with his name on wraper.Now if I am interested in steagnography approch, I am more willing to see what is inside the wraper so I will open gift without any care of wrapper.While being digital watermarking person, I am interested in wrapper rather then gift provided to me, which gives me a clear indication of the provider.The conecpt of cryptography is totally different then these approaches of data security.Digital content is encrypted at transmitter using a key and can be decrypted at receiver if and only if the correct key is available.Cryptography gives advantage only through the channel.Once encrypted content is decrypted using a key at receiver, no means of security is available for protecting digital content from copyright.Therefore, encryption must be replaced by some method which protects digital content after decryption and there concept of watermarking comes.Another difference between cryptography and watermarking is: cryptography maps the data such that it is unreadable without decryption while, watermarking embeds data maintaining multimedia in its original form. Digital watermarkingThese are the parameters important for digital watermarking.a. Transparency b.Security c.Ease of embedding and retrieval d.Robustness e.Effect on bandwidth f.Interoperability a. Transparency: The most fundamental requirement for any Watermarking method shall be such that it is transparent to the end user.The watermarked content should be consumable www.intechopen.