**6. Conclusion**

The wavelet denoising techniques offers high quality and flexibility for the noise problem of signals and image. The performances of denoising methods for several variations including thresholding rules and the type of wavelet were examined in the examples in order to put forward the suitable denoising results of the methods. The comparisons have made for the three threshold estimation methods, wavelet types and the threshold types. The examinations have showed that most important factor in wavelet denoising is what the decomposition level is rather than the wavelet type, threshold type or the estimation of threshold value.

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**22** 

*India* 

Munesh Chandra

**A DFT-DWT Domain Invisible** 

*DIT School of Engineering, Greater Noida* 

**Blind Watermarking Techniques for** 

**Copyright Protection of Digital Images** 

The great success of Internet and digital multimedia technology have made the fast communication of digital data, easy editing in any part of the digital content, capability to copy a digital content without any loss in quality of the content and many other

The great explosion in this technology has also brought some problems beside its advantages. The great facility in copying a digital content rapidly, perfectly and without limitations on the number of copies has resulted the problem of copyright protection. Digital watermarking is proposed as a solution to prove the ownership of digital data. A watermark, a secret imperceptible signal, is embedded into the original data in such a way that it remains present as long as the perceptible quality of the content is at an acceptable level. The owner of the original data proves his/her ownership by extracting the watermark

from the watermarked content in case of multiple ownership claims

In general, any watermarking scheme (algorithm) consists of three parts.

The decoder and comparator (verification or extraction or detection algorithm).

Each owner has a unique watermark or an owner can also put different watermarks in different objects the marking algorithm incorporates the watermark into the object. The verification algorithm authenticates the object determining both the owner and the integrity

Let us denote an image by *I*, a signature by *S =s1, s2, …* and the watermarked image by I′. E is an encoder function, it takes an image *I* and a signature *S*, and it generates new image

E I, S I (1)

**1. Introduction** 

The watermark.

of the object [1].

**1.1 Embedding process** 

The encoder (insertion algorithm).

which is called watermarked image *I′*, mathematically,

advantages.

